NPTF螺纹标准
FNPT与NPT与MNPT与NPTF与3_8_18NPT
FNPT与NPT与MNPT与NPTF与3/8-18NPT NPT 是National (American) Pipe Thread 的缩写，属于美国标准的60 度锥管螺纹。
NPT螺纹分：一般密封圆柱管螺纹和一般密封圆锥管螺纹二、基本尺寸：螺纹中径尺寸D2=d2=D-0.8*P螺纹小径尺寸D1=d1=D-1.6*PFNPT为内螺纹，还有个MNPT，它是外螺纹。
N.P.T为美国螺纹标准。
NPT是美标锥管螺纹National Pipe Thread的英文缩写，与国标的ZG（现在也改为NPT了）是一样的；NPTF（或者FNPT）通常指NPT的内螺纹，也就是National Pipe Thread Female;NPTM通常指NPT的外螺纹，也就是Nat ional Pipe Thread Male。
严格的说,NPTF指的是美制干密封圆锥管螺纹,牙形角60度,斜度1度47分,NP T为美制一般密封圆锥管螺纹也有通俗的说：MNPT表示阳管螺纹，FNPT表示阴管螺纹。
3/8NPT与3/8-18NPT区别3/8指的是3/8英寸（内径），也就是俗称的“三分”。
3/8：指的是3/8英寸（内径），也就是俗称的“三分”。
-18：是指每英寸螺纹牙数为18.由此也可以确定螺距为25.4/18=1.41mm。
npt3/8是60度牙形角的英制管螺纹；r3/8是55度牙形角的英制管螺纹的外螺纹。
管螺纹主要用来进行管道的连接，其内外螺纹的配合紧密，有直管与锥管两种。
公称直径是指所连接的管道直径，显然螺纹大径比公称直径大。
外螺纹是只在圆柱或者圆锥外表面的螺纹。
例如螺栓表面的螺纹即为外螺纹，而螺母的螺纹为内螺纹。
英制螺纹是螺纹尺寸用英制标注，按外形分圆柱、圆锥两种；按牙型角分55°、60°两种。
NPT一般用于管螺纹，NPT 是National (American) Pipe Thread 的缩写，属于美国标准的60度锥管螺纹，用于北美地区。
NPTF螺纹规正确使用方法
螺纹规作用：L1规是检验螺纹基面尺寸。
L3（L2）规是检验螺纹有效长度。
光规（Crest）是检验螺纹大径锥度。
螺纹规组成：L1规由Min（最小），Basic(基准)，Max（最大）三个台阶组成，Min（最小）与Max（最大）之间的距离为2T（2个螺距），它们三者之间的关系是：（T＝2个螺距） Max（最大）区域， B（基准）区域，Min（最小）区域， L2规由Min（最小），Basic(基准)，Max（最大）三个台阶组成，Min（最小）与Max（最大）之间的距离为2T（2个螺距）。
光规（Crest）由Mn和Mnt，B和BT，Mx和Mxt六个台阶组成。
检验判定方法：首先，量规及零件的螺纹必须清洁、无毛刺。
参考点在零件的端面。
端面倒角深度必须超过螺纹的小径（底径）。
1，用L1规检验螺纹；螺纹端面在最大（Max）与最小（Min）之间为合格，否则判定螺纹不合格；L1使用后，会有三种情形出现：不到基准面在1圈内；与基准面平；超过基准面在1圈内。
对于螺纹规具体位置可借助游标卡尺进行测量，根据测量的实际数值来划分属于那个位置。
三者之间的具体区域划分如下： Max（最大）＋（－）2/3T（螺距）， B(基准)±1/3T（螺距）， Min（最小）＋（－）2/3T（螺距）。
2，L1判定合格后，用L2规检验。
L2规检验螺纹；螺纹端面在最大（Max）与最小（Min）之间为合格，否则判定螺纹不合格；L2规的位置为L1规检验时位置的±1/2T（螺距），即根据L1规检验时的位置，来确定L2规是否在±1/2T（螺距）内。
即L1规在最大（Max）位置时，L2规（环规）在最大至＋1/2T内为合格，L2规（塞规）在最大至－1/2T内为合格 L1规在B基准位置时，L2规（环规与塞规）在B基准的±1/2T内为合格 L1规在最小（Min）位置时，L2规（环规）在最小至－1/2T内为合格，L2规（塞规）在最小至＋1/2T内为合格3，L1＆L2判定合格后再用Crest规（锥度规），锥度规放入螺纹内不可以有摆动。
NPTF螺纹标准[1]
![NPTF螺纹标准[1]](https://img.taocdn.com/s3/m/1cdd350af12d2af90242e62d.png)
NPT，PT，G都是管螺纹．NPT 是National (American) Pipe Thread 的缩写，属于美国标准的60 度锥管螺纹，用于北美地区．国家标准可查阅GB/T12716-1991PT 是Pipe Thread 的缩写，是55 度密封圆锥管螺纹，属惠氏螺纹家族，多用于欧洲及英联邦国家．常用于水及煤气管行业，锥度规定为1:16．国家标准可查阅GB/T730 6-2000G 是55 度非螺纹密封管螺纹，属惠氏螺纹家族．标记为G 代表圆柱螺纹．国家标准可查阅GB/T7307-2001另外螺纹中的1/4、1/2、1/8 标记是指螺纹尺寸的直径，单位是英吋．行内人通常用分来称呼螺纹尺寸，一吋等于８分，1/4 吋就是２分，如此类推．G 就是管螺纹的统称(Guan)，55，60度的划分属于功能性的，俗称管圆。
即螺纹由一圆柱面加工而成。
ZG俗称管锥，即螺纹由一圆锥面加工而成，一般的水管接头都是这样的，国标标注为Rc公制螺纹用螺距来表示，美英制螺纹用每英寸内的螺纹牙数来表示，这是它们最大的区别，公制螺纹是60度等边牙型，英制螺纹是等腰55度牙型，美制螺纹60度。
公制螺纹用公制单位，美英制螺纹用英制单位。
管螺纹主要用来进行管道的连接，其内外螺纹的配合紧密，有直管与锥管两种。
公称直径是指所连接的管道直径，显然螺纹直径比公称直径大。
1/4，1/2，1/8是英制螺纹的公称直径，单位是英寸。
、从设计角度来说，螺纹副旋合后，在基面距内应形成无隙结合。
实际上各直径、牙型角、螺距和锥角在制造中都有偏差。
NPT螺纹的牙顶和牙底为过渡配合，仅靠板紧螺纹副时的微量变形来达到100%的无隙量是不可能的。
为了确保其密封性能，往往需要螺纹副内加一定的密封介质，它主要适应于中低压系统。
NPTF螺纹的牙顶和牙底为过盈配合，扳紧螺纹副后，窄平的牙底迫使尖的牙顶弹塑性变形，因而获得100%的过盈配合，无需密封介质即能阻止泄漏，适于高压系统大径、小径不同NPTF螺纹与NPT螺纹的螺距P、基面距L1、基面上的中径d2均相同，大径、小径的计算方法也相同，但因两者牙高不同，所以大径小径并不相同。
NPTF标准
管螺纹标准55度管螺纹：主要用来进行管道的连接，使其内外螺纹的配合紧密，有直管和锥管两种。
常见的管螺纹主要包括以下几种：NPT、PT、G等。
1）NPT是National(American)Pipe⌝ Thread的缩写，属于美国标准的60度椎管螺纹，用于北美地区，国标查阅GB/T12716-1991。
2）PT（BSPT）是Pipe Thread⌝的缩写，是55度密封圆椎管螺纹，属于惠氏螺纹家族，多用于欧洲及英联邦国家，常用于水及煤气管行业，锥度1:16，国标查阅GB/T7306-2000。
国内叫法为ZG.。
3）G是55度非螺纹密封管螺纹，属惠氏螺纹家族。
标记为G代表圆柱螺纹。
国标查阅GB/T7307-2001。
⌝公制螺纹与英制螺纹的区别：公制螺纹用螺距来表示，美英制螺纹用每英寸内的螺纹牙数来表示；公制螺纹是60度等边牙型，英制螺纹是等腰55度牙型，美制螺纹为等腰60度牙型；公制螺纹用公制单位（如mm），美英制螺纹用英制单位（如英寸）；“行内人”通常用“分”来称呼螺纹尺寸，一英寸等于8分，1/4英寸就是2分，以此类推。
另外还有：ISO—公制螺纹标准60度；UN—统一螺纹标准60度；API—美国石油管螺纹标准60度；W—英国惠氏螺纹标准55度；NPT BSP螺纹技术---- NPT，PT，G螺纹的区别NPT，PT，G各种螺纹的区别NPT，PT，G都是管螺纹．NPT 是 National (American) Pipe Thread 的缩写，属于美国标准的 60 度锥管螺纹，用于北美地区．国家标准可查阅 GB/T12716-1991PT 是 Pipe Thread 的缩写，是 55 度密封圆锥管螺纹，属惠氏螺纹家族，多用于欧洲及英联邦国家．常用于水及煤气管行业，锥度规定为 1:16．国家标准可查阅 GB/T7306-2000G 是 55 度非螺纹密封管螺纹，属惠氏螺纹家族．标记为 G 代表圆柱螺纹．国家标准可查阅 GB/T7307-2001另外螺纹中的1/4、1/2、1/8 标记是指螺纹尺寸的直径，单位是英寸．行内人通常用分来称呼螺纹尺寸，一等于８分，1/4 ?就是２分，如此类推．G 就是管螺纹的统称(Guan)，55，60度的划分属于功能性的，俗称管圆。
NPTF螺纹标准
NPTF螺纹标准NPT，PT，G都是管螺纹．NPT是National(American)PipeThread的缩写，属于美国标准的60度锥管螺纹，用于北美地区．国家标准可查阅GB/T12716-1991PT是PipeThread的缩写，是55度密封圆锥管螺纹，属惠氏螺纹家族，多用于欧洲及英联邦国家．常用于水及煤气管行业，锥度规定为1:16．国家标准可查阅GB/T7306-2000G是55度非螺纹密封管螺纹，属惠氏螺纹家族．标记为G代表圆柱螺纹．国家标准可查阅GB/T7307-2001另外螺纹中的1/4、1/2、1/8标记是指螺纹尺寸的直径，单位是英吋．行内人通常用分来称呼螺纹尺寸，一吋等于８分，1/4吋就是２分，如此类推．G就是管螺纹的统称(Guan)，55，60度的划分属于功能性的，俗称管圆。
即螺纹由一圆柱面加工而成。
ZG俗称管锥，即螺纹由一圆锥面加工而成，一般的水管接头都是这样的，国标标注为Rc公制螺纹用螺距来表示，美英制螺纹用每英寸内的螺纹牙数来表示，这是它们最大的区别，公制螺纹是60度等边牙型，英制螺纹是等腰55度牙型，美制螺纹60度。
公制螺纹用公制单位，美英制螺纹用英制单位。
管螺纹主要用来进行管道的连接，其内外螺纹的配合紧密，有直管与锥管两种。
公称直径是指所连接的管道直径，显然螺纹直径比公称直径大。
1/4，1/2，1/8是英制螺纹的公称直径，单位是英寸。
、从设计角度来说，螺纹副旋合后，在基面距内应形成无隙结合。
实际上各直径、牙型角、螺距和锥角在制造中都有偏差。
NPT螺纹的牙顶和牙底为过渡配合，仅靠板紧螺纹副时的微量变形来达到100%的无隙量是不可能的。
为了确保其密封性能，往往需要螺纹副内加一定的密封介质，它主要适应于中低压系统。
NPTF螺纹的牙顶和牙底为过盈配合，扳紧螺纹副后，窄平的牙底迫使尖的牙顶弹塑性变形，因而获得100%的过盈配合，无需密封介质即能阻止泄漏，适于高压系统大径、小径不同NPTF螺纹与NPT螺纹的螺距P、基面距L1、基面上的中径d2均相同，大径、小径的计算方法也相同，但因两者牙高不同，所以大径小径并不相同。
NPTF 内螺纹检查方法
NPTF 內螺紋檢查方法：NPTF內螺紋有兩個等級，為NPTF-1和NPTF-2，其檢查方法如下：NPTF 內螺紋須同時滿足L1、L3牙規和6 Step光滑錐度規的檢查方為合格。
L1牙規:L1牙規上有三個台位，為MIN、BASIC和MAX，當用L1牙規檢查時，工件端面必須位於MIN和MAX之間方為合格，否則為不合格。
L3牙規:L3牙規上也有三個台位，同樣為MIN、BASIC和MAX，當用L3牙規檢查時，工件端面必須位於MIN和MAX之間為合格，否則為不合格。
6 Step光滑錐度規：6 Step 規上共有6個台位，分別為MN、MNT、B、BT、MX和MXT。
分為三種情況：1) 當用L1牙規檢查工件時，產品基面若位於MIN~MIN+2/3轉時，應用6 Step的MN和MNT 兩個台階來判斷，即工件基面須位於MN和MNT之間方為合格。
2) 當用L1牙規檢查工件時，產品基面若位於BASIC+/-1/3轉時，應用6 Step的B和BT兩個台階來判斷，即工件基面須位於B和BT之間方為合格。
3) 當用L1牙規檢查工件時，產品基面若位於MAX-2/3轉到MAX面之間，應用6 Step的MX 和MXT兩個台階來判斷，即工件基面須位於MX和MXT之間方為合格（L1是检测前面的1－4个牙，第一牙如与基准面相平是最好的，如做不到只能是正负半个牙；L2规是检测整个螺孔的锥度的，也叫6 step,B，BT是基准面，MX，MXT是最大值，如果MXT掉入第一圈牙以下即为NG，MN，MNT是最小值，如MN不能掉入第一圈牙即为NG，说明孔小了，它们2者之间相差0.5圈；L3规是检测后面3圈牙的，与L1一样使用。
）NPTF的检验要检验3个长度，分别是：L1＝手动旋合长度（就是用手拧，只能拧进去的这个长度）L2＝是这个尺寸（如1/4英寸）的管螺纹的总有效牙数的长度L3＝就是上扳手之后，在L1的基础上，要保证能用扳手再拧进去的三个牙的长度。
npt螺纹标准对照表
npt螺纹标准对照表NPT螺纹标准对照表。
NPT螺纹是一种常见的管道螺纹标准，它被广泛应用于液体传输、气体传输和密封连接等领域。
在实际应用中，我们经常需要对照不同的NPT螺纹标准，以确保管道连接的质量和稳定性。
本文将介绍NPT螺纹标准对照表，帮助大家更好地理解和应用NPT螺纹标准。
NPT螺纹标准对照表如下：1. NPT螺纹尺寸对照表。
NPT螺纹的尺寸是指其直径和螺距的大小。
在实际应用中，我们需要根据管道的尺寸和要求来选择合适的NPT螺纹标准。
以下是常见的NPT螺纹尺寸对照表：1/8 NPT，螺纹直径为0.405英寸，螺距为27个螺纹每英寸。
1/4 NPT，螺纹直径为0.540英寸，螺距为18个螺纹每英寸。
3/8 NPT，螺纹直径为0.675英寸，螺距为18个螺纹每英寸。
1/2 NPT，螺纹直径为0.840英寸，螺距为14个螺纹每英寸。
2. NPT螺纹密封对照表。
NPT螺纹的密封是非常重要的，它直接影响到管道连接的质量和稳定性。
在选择NPT螺纹标准时，我们需要注意其密封性能。
以下是常见的NPT螺纹密封对照表：NPTF，带有圆锥密封的NPT螺纹，适用于高压液体和气体传输。
NPTM，带有平面密封的NPT螺纹，适用于一般液体和气体传输。
NPTS，带有密封垫的NPT螺纹，适用于特殊要求的液体和气体传输。
3. NPT螺纹材质对照表。
NPT螺纹的材质也是非常重要的，它直接影响到管道连接的耐腐蚀性能和使用寿命。
在选择NPT螺纹标准时，我们需要注意其材质特性。
以下是常见的NPT螺纹材质对照表：黄铜NPT螺纹，具有良好的耐腐蚀性能，适用于一般液体和气体传输。
不锈钢NPT螺纹，具有优异的耐腐蚀性能，适用于腐蚀性液体和气体传输。
铝NPT螺纹，具有轻质和良好的导热性能，适用于特殊要求的液体和气体传输。
4. NPT螺纹标准符号对照表。
NPT螺纹的标准符号是指其在图纸和规范中的表示方法。
在实际应用中，我们需要根据标准符号来识别和区分不同的NPT螺纹标准。
NPT,NPTF,PT,G各种螺纹的区别
NPT，PT，G各种螺纹的区别NPT，PT，G都是管螺纹．1、NPT 是National (American) Pipe Thread 的缩写，属于美国标准的60 度锥管螺纹（牙型角为60°、螺纹锥度为1：16的管螺纹），用于北美地区．国家标准可查阅国家标准GB/T12716-1991（我国过去规定为K，后来规定为Z，现在改为NPT）；2、NPT ：美制一般用途圆锥管螺纹（密封）NPTF：美制干密封圆锥管螺纹使用时前者可以在螺纹副内填加密封介质，而后者则完全依靠螺纹自身形成密封，螺纹间无任何密封介质。
所以前者属于经济型螺纹，产品设计中常用，而干密封管螺纹则规定了较为严格的公差，属精密型螺纹，仅用在特殊场合。
它们两者的牙型角、斜度等指标都是相同的，关键是牙顶和牙底的削平高度不一样（螺纹牙高不一样。
NPT可能有过盈也可能有间隙，但NPTF没有间隙；NPT内外螺纹均为圆锥，而NPTF外螺纹是圆锥，内螺纹则有圆锥、圆柱两种；NPT有右旋也有左旋，NPTF只有右旋一种旋向。
）3、PT 是Pipe Thread 的缩写，是55 度密封圆锥管螺纹，属惠氏螺纹家族，多用于欧洲及英联邦国家．常用于水及煤气管行业，锥度规定为1:16．国家标准可查阅GB/T7306-20004、G 是55 度非螺纹密封管螺纹，属惠氏螺纹家族．标记为G 代表圆柱螺纹．国家标准可查阅GB/T7307-2001 另外螺纹中的1/4、1/2、1/8 标记是指螺纹尺寸的直径，单位是英寸．行内人通常用分来称呼螺纹尺寸，一英寸等于８分，1/4 英寸就是２分，如此类推5、G 就是管螺纹的统称(Guan)，55，60度的划分属于功能性的，俗称管圆。
即螺纹由一圆柱面加工而成。
6、ZG俗称管锥，即螺纹由一圆锥面加工而成，一般的水管接头都是这样的，国标标注为Rc7、公制螺纹用螺距来表示，美英制螺纹用每英寸内的螺纹牙数来表示，这是它们最大的区别，公制螺纹是60度等边牙型，英制螺纹是等腰55度牙型，美制螺纹60度。
美国标准管螺纹(National Pipe Tapered)
NPT代表美国标准管螺纹(National Pipe Tapered) ，NPTF则是干密封式美国标准管螺纹。
两者基本牙型是一样的，不同点是：∙螺纹牙高不一样。
NPT可能有过盈也可能有间隙，但NPTF没有间隙；∙NPT内外螺纹均为圆锥，而NPTF外螺纹是圆锥，内螺纹则有圆锥、圆柱两种；∙NPT有右旋也有左旋，NPTF只有右旋一种旋向。
NPTF NPTM螺纹是什么意思？NPT：National (American) Pipe Thread美国管螺纹。
F：Female内螺纹。
M：Male外螺纹。
国家螺纹管标准ANSI B1.20.1Characteristics of NPT (also known as ANSI/ASME B1.20.1 Pipe Threads, General Purpose):该标准规定:tapered thread 1o 47' 锥形螺纹1度47分truncation of roots and crests are flat 顶部和根部的截断面是平的60o thread angle 60度的螺纹断面角pitch is measured in threads per inch 单位罗纹数以每英寸计算Note! Pipe sizes do not refer to any physical dimensions. The outside diameter of a pipe or fitting must be measured and compared to a table for size identification. A 3/4" NPT pipe thread has an outside diameter - OD - of 1.050 inches.备注：管的尺寸不是指物理容积。
管的外部直径和属性必须以下面这个表格来确定。
例如：一个标准为3/4" NPT的管外部直径为1.050英寸。
美国标准管螺纹(National Pipe Tapered)
NPT代表美国标准管螺纹(National Pipe Tapered) ，NPTF则是干密封式美国标准管螺纹。
两者基本牙型是一样的，不同点是：∙螺纹牙高不一样。
NPT可能有过盈也可能有间隙，但NPTF没有间隙；∙NPT内外螺纹均为圆锥，而NPTF外螺纹是圆锥，内螺纹则有圆锥、圆柱两种；∙NPT有右旋也有左旋，NPTF只有右旋一种旋向。
NPTF NPTM螺纹是什么意思？NPT：National (American) Pipe Thread美国管螺纹。
F：Female内螺纹。
M：Male外螺纹。
国家螺纹管标准ANSI B1.20.1Characteristics of NPT (also known as ANSI/ASME B1.20.1 Pipe Threads, General Purpose):该标准规定:tapered thread 1o 47' 锥形螺纹1度47分truncation of roots and crests are flat 顶部和根部的截断面是平的60o thread angle 60度的螺纹断面角pitch is measured in threads per inch 单位罗纹数以每英寸计算Note! Pipe sizes do not refer to any physical dimensions. The outside diameter of a pipe or fitting must be measured and compared to a table for size identification. A 3/4" NPT pipe thread has an outside diameter - OD - of 1.050 inches.备注：管的尺寸不是指物理容积。
管的外部直径和属性必须以下面这个表格来确定。
例如：一个标准为3/4" NPT的管外部直径为1.050英寸。
NPT和NPTF螺纹有什么区别
NPT和NPTF螺纹有什么区别？NPT：使用中要在螺纹副内加入密封添料NPTF：美制干密封圆锥管螺纹完全依靠螺纹自身形成密封，螺纹间无任何密封介质。
NPT（National Pipe Thread ）美制一般密封圆锥管螺纹NPTF（Nation pipe taper）美制标准干密封圆锥管螺纹NPSM（American Standard Straight Pipe Thread for Me-chanical Joints）美国标准机械接头直管螺纹NPT 是National (American) Pipe Thread 的缩写，属於美国标准的60 度锥管螺纹，用於北美地区．国家标准可查阅GB/T12716-1991。
nptfF中的F是指：Female内螺纹NPTF螺纹称之为干密封式锥管螺纹，它连接密封的原理是在没有润滑剂或密封填料情况下螺纹连接时，设计意图是使内、外螺纹牙的侧面、牙顶和牙底同时接触，来达到密封的目的。
NPT螺纹称之为一般用途的锥管螺纹，这也是我们以前称之为的布氏锥螺纹。
它们两者的牙型角、斜度等指标都是相同的，关键是牙顶和牙底的削平高度不一样，所以，量规的设计也是不一样的。
10回答者：jack6308 - 七级/4 NPT 圆锥管螺纹的锥度怎么计算NPT②一般用途的锥管螺纹是美国标准ANSIB 牙型角为60°的英制管螺纹相当于我国的60°圆锥管螺纹GB/T12716-1991名称＝60°圆锥管螺纹的基本牙型和基本尺寸标准=摘自GB/T 12716-1991单位=(mm)-----------------------------------------------------------尺寸代号=1/4每25.4(mm)内的牙数n=18装配余量L3\牙数=3圆锥外螺纹小端面处的螺纹小径=10.997参考资料：《机械设计手册》锥度是1:16啊,/16)端面的小径=基面小径11.358+(基准距离5.786X1/16)1/4-18 NPT 圆锥管螺纹的大小外径怎么计算计算公式悬赏分：0 - 提问时间2009-9-20 02:58提问者：wenming1683 - 一级其他回答共1 条1/4-18 NPT 圆锥管螺纹的大小外径怎么计算计算公式螺纹标准的一种，按外形分圆柱、圆锥两种；按牙型角分55°、60°两种。
公制美制管螺纹标准-NPTF
61.223 60.483
59.282
20.32
18.11
74.042 73.282
71.476
30.48
27.31
90.897 90.157
87.252
32.07
28.89
21
© Hunan Oil Pump Co., Ltd 2009
5、螺纹检验；
NPTF干密封管螺纹
1）：L1锥螺纹塞规，全螺纹，有三个台阶，为“上”、“0”、“下”
1/8-27 1/27(0.941)
1/4-18 1/18(1.411)
3/8-18 1/18(1.411)
1/2-14 1/14(1.814)
3/4-14 1/14(1.814)
1-11 1/2 2/23(2.209)
1 1/4-11 1/2 2/23(2.209)
1 1/2-11 1/2 2/23(2.209)
国家（美国）标 准，P：管（公称 管）T：圆锥， S：圆柱，F：燃 料和油，I：中间
的，
15
© Hunan Oil Pump Co., Ltd 2009
2：美国标准标注方式
NPTF干密封管螺纹
1-
1表 示螺 纹公 称尺 寸， 单位 为英 寸
11 ½
螺距为 1/11.5， 即每英 寸11.5 牙，具 体螺纹 规格见 表四；
2.4 2.4
加工螺纹大端大径D2 螺纹小端大
螺纹长度L
最大尺寸 最小尺寸
径D1
最大尺寸 最小尺寸
mm
mm
mm
mm
mm
8.169
7.939
7.525
7.10
6.16
10.519 10.289
1okj8-27NPTF美国干密封螺纹的参数螺距003704
1/8-27NPTF美国干密封螺纹的参数：螺距：0.03704；外螺纹端头中径：0.36351；手旋合长度：0.1615（4.36牙）；完整外螺纹基本长度：0.2639（7.12牙）；螺尾V加螺纹公差加凸肩余隙（V+3P/2）：0.1112（3.072牙）；凸肩长度（L2+3P）：0.3750；外螺纹拧紧距离：0.1024（2.76牙）；接头外螺纹：0.407；中径上的锥度：11/16~13/16(单位：英寸/英尺)；螺纹有效长度内的导程：±0.001；螺纹半角30°±1°；螺纹基本三角形高度：0.03208；螺纹牙高：0.02341～0.02685；削平量：（牙顶）0.0017～0.0035；相当的削平宽度：0.002.～0.0040。
核心提示：在生活中，长相平凡的我们总是羡慕那些“白富美”，觉得那是女人的骄傲，魔鬼身材天使样貌。
而长得逊色的我们总会自卑，样子不好身材不好。
但是，上帝给你关了一扇门,必然会为你开启一扇窗。
有研究表明，女性8大部位越丑越健康，现在小编和大家一起来看看为我们健康自豪的8大部位吧。
在生活中，我们会质疑上帝为什么那么不公平，把所有好的一切都给了“白富美”，而长相平凡的我们只能其貌不扬，在人群中都会被淹没。
其实，上帝是公平的，有研究表明，丑也是一种健康，身体有些部位越丑表示我们的身体越健康。
1、乳房小——脊柱更挺拔研究发现，乳房越大，尤其是D罩杯以上的人，越容易出现上背痛及脊柱弯曲，乳房小的人则不会。
2、屁股大——心脑血管好多项研究显示，臀部大的人体内“坏胆固醇”水平更低，“好胆固醇”水平更高，因而心脑血管硬化的几率较小。
而且大屁股的人患糖尿病的风险也很低。
3、耳朵大——老了不失聪生物医学指出，人的外耳越大，耳道获得的声音就越清晰，因此大耳朵的人很少因衰老而失聪。
4、长痣多——老得慢身上痣多不仅难看，而且会使患皮肤癌风险增加10倍。
FNPT与NPT与MNPT与NPTF与3_8_18NPT
FNPT与NPT与MNPT与NPTF与3/8-18NPT NPT 是National (American) Pipe Thread 的缩写，属于美国标准的60 度锥管螺纹。
NPT螺纹分：一般密封圆柱管螺纹和一般密封圆锥管螺纹二、基本尺寸：螺纹中径尺寸D2=d2=D-0.8*P螺纹小径尺寸D1=d1=D-1.6*PFNPT为内螺纹，还有个MNPT，它是外螺纹。
N.P.T为美国螺纹标准。
NPT是美标锥管螺纹National Pipe Thread的英文缩写，与国标的ZG（现在也改为NPT了）是一样的；NPTF（或者FNPT）通常指NPT的内螺纹，也就是National Pipe Thread Female;NPTM通常指NPT的外螺纹，也就是Nat ional Pipe Thread Male。
严格的说,NPTF指的是美制干密封圆锥管螺纹,牙形角60度,斜度1度47分,NP T为美制一般密封圆锥管螺纹也有通俗的说：MNPT表示阳管螺纹，FNPT表示阴管螺纹。
3/8NPT与3/8-18NPT区别3/8指的是3/8英寸（内径），也就是俗称的“三分”。
3/8：指的是3/8英寸（内径），也就是俗称的“三分”。
-18：是指每英寸螺纹牙数为18.由此也可以确定螺距为25.4/18=1.41mm。
npt3/8是60度牙形角的英制管螺纹；r3/8是55度牙形角的英制管螺纹的外螺纹。
管螺纹主要用来进行管道的连接，其内外螺纹的配合紧密，有直管与锥管两种。
公称直径是指所连接的管道直径，显然螺纹大径比公称直径大。
外螺纹是只在圆柱或者圆锥外表面的螺纹。
例如螺栓表面的螺纹即为外螺纹，而螺母的螺纹为内螺纹。
英制螺纹是螺纹尺寸用英制标注，按外形分圆柱、圆锥两种；按牙型角分55°、60°两种。
NPT一般用于管螺纹，NPT 是National (American) Pipe Thread 的缩写，属于美国标准的60度锥管螺纹，用于北美地区。
标准SAE J476-1961 美制干密封管螺纹(NPTF) DRYSEAL PIPE THREADS
SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243TO PLACE A DOCUMENT ORDER; (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS SURFACE VEHICLE 400 Commonwealth Drive, Warrendale, PA 15096-0001STANDARDSubmitted for recognition as an American National StandardJ476aREV.JUN61Issued 1921-03Revised1961-06Superseding J476DRYSEAL PIPE THREADSForeword—This Document has not changed other than to put it into the new SAE Technical Standards Board Format.TABLE OF CONTENTS1.Scope.......................................................................................................................................................22.References...............................................................................................................................................22.1Applicable Publications.............................................................................................................................23.T runcation—Dryseal American Standard External and Internal Pipe Threads ........................................23.1Thread Form.............................................................................................................................................23.2Thread Series Symbols............................................................................................................................23.3Thread Designation..................................................................................................................................23.4Straight Pipe Threads...............................................................................................................................34.Dryseal American Standard Pipe Thread (NPTF)....................................................................................45.Dryseal SAE Short External T aper Pipe Thread (PTF—SAE Short External).........................................56.Dryseal SAE Short Internal T aper Pipe Thread (PTF—SAE Short Internal)............................................67.Dryseal American Standard Fuel Internal Straight Pipe Thread (NPSF).................................................78.Dryseal American Intermediate Internal Straight Pipe Thread (NPSI) (8)Appendix A Supplementary Thread Information..........................................................................................................9Appendix B Chaser and T ap Information...................................................................................................................13Appendix C Dryseal Pipe Thread Gaging..................................................................................................................17Appendix D Special and Fine Dryseal Pipe Threads.................................................................................................41Appendix E Superseded Gage Dimensions and Gaging Practice for 1/8 and 1/4 Size Dryseal Pipe Threads (46)1.Scope—The Dryseal American Standard Taper Pipe Thread, the Dryseal American Fuel Internal Straight PipeThread and the Dryseal American Intermediate Internal Straight Pipe Thread covered by this standard conform with the American Standard ASA-B2.2. The Dryseal SAE-Short T aper Pipe Thread in this standard conforms with the Dryseal American Standard T aper Pipe Thread except for the length of thread, which is shortened for increased clearance and economy of material.The significant feature of the Dryseal thread is controlled truncation at the crest and root to assure metal to metal contact coincident with or prior to flank contact. Contact at the crest and root prevents spiral leakage and insures pressure-tight joints without the use of a lubricant or sealer.Lubricants, if not functionally objectionable, may be used to minimize the possibility of galling in assembly.2.References2.1Applicable Publications—The following publications form a part of the specification to the extent specifiedherein. Unless otherwise indicated the latest revision of SAE publications shall apply.2.1.1SAE P UBLICATIONS—Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.ASA B2.2—Dryseal Pipe ThreadsSAE Standards Screw Threads3.Truncation—Dryseal American Standard External And Internal Pipe Threads For Pressure-Tight JointsWithout Lubricant Or Sealer3.1Thread Form—The angle between the flanks of the thread is 60 deg when measured on an axial plane andthe line bisecting this angle is perpendicular to the axis of both the taper and straight threads.Diametral taper of tapered threads is 0.75 in. ± 0.06 in. per 12.00 in. of length.Although the crests and roots of the Dryseal threads are theoretically flat, they may be rounded provided their contour is within the limits specified in T able 1.3.2Thread Series Symbols—The identification symbols which have been adopted for designating the variousDryseal Pipe Thread Series are as follows:NPTF for Dryseal American Standard T aper Pipe Thread.PTF—SAE for Dryseal SAE Short T aper Pipe Thread.NPSF for Dryseal American Fuel Internal Straight Pipe Thread.NPSI for Dryseal American Intermediate Internal Straight Pipe Thread.Where: N stands for American Standard [formerly American (National) Standard].P stands for PipeT stands for T aperF stands for FuelS stands for StraightI stands for Intermediate3.3Thread Designation—Dryseal pipe threads are designated by specifying in sequence the nominal size,number of threads per inch, form (Dryseal), and symbol of the thread series.EXAMPLE—1/8—27 DRYSEAL NPTF1/8—27 DRYSEAL PTF—SAE SHORT1/8—27 DRYSEAL NPSF1/8—27 DRYSEAL NPSI3.4Straight Pipe Threads—An assembly with straight internal pipe threads and taper external pipe threads isfrequently more advantageous than an all taper thread assembly, particularly in automotive and other allied industries where economy and rapid production are paramount considerations. Dryseal threads are not used on assemblies in which both components have straight pipe threads.FIGURE 1—4.Dryseal American Standard Taper Pipe Thread (NPTF)—This series applies to both the external and internal threads of all full length and is suitable for pipe joints in practically every type of service. These threads are generally conceded to be superior for strength and seal. Use of the tapered internal thread in hard or brittle materials having thin sections will minimize trouble from fracture. Dimensional data for (NPTF) threads is given in T able 2. See Appendix D for limitations of assembly of NPTF threads with other series Dryseal pipe threads.FIGURE 2—TABLE 1—LIMITS ON CREST AND ROOT TRUNCATIONThreads perin.Depth of Sharp-V Thread, Hin.Truncation Min Formula Truncation Min in.Truncation Max Formula TruncationMax in.Equalivalent Width of Flat (1)Min Formula 1.The major diameter of plug gages and minor diameter of ring gages used for gaging dryseal threads shall be truncated an amount sufficient to produce a flat width as shown in Appendix C, Tables C1-1 to C12-1 inclusive.Equivalent Width of Flat (1)Min in.Equivalent Width of Flat (1)Max Formula Equivalent Width ofFlat (1)Max in.27 Crest 0.032080.047p 0.00170.094p 0.00350.054p 0.00200.108p 0.0040 Root 0.094p0.00350.140p 0.00520.108p 0.00400.162p 0.006018 Crest 0.048110.047p 0.00260.078p 0.00430.054p 0.00300.090p 0.0050 Root 0.078p0.00430.109p 0.00610.090p 0.00500.126p 0.007014 Crest 0.061860.036p 0.00260.060p 0.00430.042p 0.00300.070p 0.0050 Root 0.060p0.00430.085p 0.00610.070p 0.00500.098p 0.007011-1/2 Crest 0.075310.040p 0.00350.060p 0.00520.046p 0.00400.069p 0.0060 Root 0.060p0.00520.090p 0.00780.069p 0.00600.103p 0.0090 8 Crest 0.108250.042p 0.00520.055p 0.00690.048p 0.00600.064p 0.0080(2)2.There is reason to doubt the correctness of the 8 threads per in. flat widths on account of the volume of metal to be displaced.Root 0.055p0.00690.076p0.00950.064p0.00800.088p0.01105.Dryseal SAE Short External Taper Pipe Thread (PTF—SAE Short External) For Assembly With DrysealAmerican Intermediate Internal Straight (Table 6) or Dryseal American Standard Taper (Table 2) Pipe Threads—External threads of this series conform in all respects with the NPTF threads except that the full thread length has been shortened by eliminating one thread from the small end. These threads are primarily intended for assembly with NPSI internal threads but may also be used with NPTF internal threads. They are not designed for and at extreme tolerance limits may not assemble with PTF—SAE Short or NPSF internal threads. Dimensional data for PTF—SAE Short External Threads is given in T able 3. See Appendix D for limitations of assembly of PTF—SAE Short external threads with other series Dryseal pipe threads.FIGURE 3—TABLE 2—BASIC DIMENSIONS OF DRYSEAL AMERICAN STANDARD TAPER PIPE THREAD (1)1.See general specifications preceding tables.For gaging methods, gages, cut thread blanks, taps, drilled hole sizes, hole depths, and full thread lengths, see Appendixes A, B, and C.NPTFSize 1Pitch,P in.2Pitch Diameter at End of External Thread, E 0in.3Pitch Diameter at End of Internal Thread,E 1in.4Hand Engage-ment,L 1in.5Hand Engage-ment,L 1Thread 6Length of Full Thread,(2)L 2in.72.External thread tabulated full thread lengths include chamfers not exceeding one and one-half pitches (threads) length.Length of FullThread (2), L 2Thread8Vanish Threads V Plus FullThreadTolerance PlusShoulderClearance (V + 1p +1/2 p) in.9Vanish Threads V PlusFull Thread Tolerance Pluls Shoulder Clearance (V + 1p + 1/2 p) Thread 10Shoulder Length L 2 + (3p Approx)in.11External Thread for Draw (L 2 - L 1)in.12External Thread for Draw (L 2 - L 1) Thread 13 Length of Internal Full Thread,(3) (L 1 + L 3)in.143.Internal thread tabulated full thread lengths do not include countersink beyond the intersection of the pitch line and the chamfer cone(gaging reference point).Length ofInternal Full Thread (3)(L 1 + L 3) Thread15OD of Fitting, D 2in. 16OD of Pipe,D1/16-270.037040.271180.281180.160 4.320.26117.050.1139 3.0750.37500.1011 2.730.27117.320.3150.3125 1/8 -270.037040.363510.373600.1615 4.360.26397.120.1112 3.0720.37500.1024 2.760.27267.360.4070.405 1/4 -180.055560.477390.491630.2278 4.100.40187.230.1607 2.8920.56250.1740 3.130.39457.100.5460.540 3/8 -180.055560.612010.627010.2404.320.40787.340.15472.7910.56250.16783.020.40677.320.6810.6751/2 -140.071430.758430.778430.320 4.480.53377.470.2163 3.0280.75000.2137 2.990.53437.480.8500.840 3/4 -140.071430.967680.988870.339 4.750.54577.640.2043 2.8600.75000.2067 2.890.55337.75 1.060 1.0501 -11-1/20.08696 1.21363 1.238630.400 4.600.68287.850.2547 2.9290.93750.2828 3.250.66097.60 1.327 1.3151-1/4 -11-1/20.086961.557131.583380.4204.830.70688.130.26203.0130.96880.28683.300.68097.831.6721.6601-1/2 -11-1/20.08696 1.79609 1.822340.420 4.830.72358.320.2765 3.180 1.00000.3035 3.490.68097.83 1.912 1.900 -11-1/20.08696 2.26902 2.296270.436 5.010.75658.700.2747 3.159 1.03120.3205 3.690.69698.01 2.387 2.3752-1/2 -80.12500 2.71953 2.762160.682 5.46 1.13759.100.3781 3.025 1.51560.4555 3.64 1.05708.46 2.893 2.8753 -80.125003.340623.388500.7666.131.20009.600.37813.0251.57810.43403.471.14109.133.5183.5006.Dryseal SAE Short Internal Taper Pipe Thread (PTF—SAE Short Internal) For Assembly With AmericanStandard External Taper Pipe Thread (Table 2)—Internal Threads of this series conform in all respects with the NPTF threads except that the full thread length has been shortened by eliminating one thread from the large end. These threads are primarily intended for assembly with NPTF external threads. They are not designed for and at extreme tolerance limits may not assemble with PTF—SAE Short external threads.Dimensional data for PTF—SAE Short Internal Threads is given in Table 4. See Appendix D for limitations of assembly of PTF—SAE Short internal threads with other series Dryseal pipe threads.T rouble-free assemblies and pressure-tight joints without the use of lubricant or sealer can best be assured where both components are threaded with NPTF (full length) threads. This should be considered before specifying PTF—SAE Short External or Internal Thread.FIGURE 4—TABLE 3—BASIC DIMENSIONS OF DRYSEAL SAE SHORT EXTERNAL TAPER PIPE THREAD (1)1.See general specifications preceding tables.For gaging methods, gages, cut thread blanks, taps, drilled hole sizes, hole depths, and full thread lengths, see Appendixes A, B, and C.PTF—SAE Short Size1Pitch, P in.2Pitch Diameter at End of External Thread,E 0 Shortin.3L 1in.4L 1Thread 5Hand Engage-ment,L 1 Short in.6Hand Engage-ment, L 1 Short Thread 7Length of Full Thread,(2) L 2 Short 82.External thread tabulated full thread lengths include camfers not exceeding one and one-half pitches (threads) lengths.Length of FullThread,(2)L2 Short Thread 9Vanish Threads V Plus Full Thread Tolerance Plus Shoulder Clearance (V + 1p + 1/2 p)in.10Vanish Threads V Plus Full Thread Tolerance Plus Shoulder Clearance (V + 1p + 1/2 p)Thread 11Min ShoulderLength (L 2 Short +2-1/2 p)in.12External Thread for Draw (L 2 Short—L1 Short)in.13External Thread for Draw (L 2 Short—L1 Short)Thread 14 Length of Internal Full Thread,(3) (L 1 Short + 4p)in.153.Internal thread tabulated full thread lengths do not include countersink beyond the intersection of the pitch line and the camfercone (gaging reference point).Length of Internal Full Thread (3),(L 1 Short + 4p)Thread 16 1/16-270.037040.27349 0.160 4.320.1230 3.320.2241 6.050.0926 2.500.31670.1011 2.730.27117.32 1/8 -270.037040.36582 0.1615 4.360.1244 3.360.2268 6.120.0926 2.500.31940.1024 2.760.27267.36 1/4 -180.055560.48086 0.2278 4.100.1722 3.100.3462 6.230.1389 2.500.48510.1740 3.130.39457.10 3/8 -180.055560.615480.2404.320.18443.320.35226.340.13892.500.49110.16783.020.40677.321/2 -140.071430.76289 0.320 4.480.2486 3.480.4623 6.470.1786 2.500.64090.2137 2.990.53437.48 3/4 -140.071430.97214 0.339 4.750.2676 3.750.4743 6.640.1786 2.500.65280.2067 2.890.55337.751 -11-1/20.08696 1.21906 0.400 4.600.3130 3.600.5958 6.850.2174 2.500.81320.2828 3.250.66097.601-1/4 -11-1/20.086961.562560.4204.830.33303.830.61987.130.21742.500.83720.28683.300.68097.831-1/2 -11-1/20.08696 1.80152 0.420 4.830.3330 3.830.63657.320.2174 2.500.85390.3035 3.490.68097.832 -11-1/20.08696 2.27445 0.436 5.010.3490 4.010.66957.700.2174 2.500.88690.3205 3.690.69698.012-1/2 -80.12500 2.72734 0.682 5.460.5570 4.46 1.01258.100.3125 2.50 1.32500.4555 3.64 1.05708.46 -80.125003.348440.7666.130.64105.131.07508.600.31252.501.38750.43403.471.14109.137.Dryseal American Standard Fuel Internal Straight Pipe Thread (NPSF) For Assembly With Dryseal American Standard External Taper Pipe Thread (Table 2)—Threads of this series are straight (cylindrical)instead of tapered. They are generally used in soft or ductile materials which will adjust at assembly to the taper of external threads but may also be used in hard or brittle materials where the section is heavy. These threads are primarily intended for assembly with full length NPTF external taper threads. Dimensional data for NPSF threads is given in Table 5. See Appendix D for limitations of assembly of NPSF internal threads with other series Dryseal pipe threads.TABLE 4—BASIC DIMENSIONS OF DRYSEAL SAE SHORT INTERNAL TAPER PIPE THREAD (1)1.See general specification preceding table.For gaging methods, gages, taps, drilled hole sizes, hole depths, and full thread lengths, see Appendixes A, B, and C.PTF—SAEShort Size1Pitch P in.2Pitch Diameter at End of Internal Thread E 1 Shortin.3L 1in.4L 1Thread 5Hand Engage-ment,(2)L 1 Short62.Internal thread tabulated full thread lengths do not include countersink beyond the intersection of the pitch line and the chamfer cone (gaging reference point).HandEngage-ment,(2)L 1 Short Thread 7Length of Internal Full Thread (2)(L 1 Short + L 3)in.8Length of Internal FullThread (2) (L 1 Short + L 3)Thread9Hole Depth forSAE Short Tap(Table B3)in.10 1/16-270.037040.278870.160 4.320.1230 3.320.2341 6.320.4564 1/8 -270.037040.371290.1615 4.360.1244 3.360.2356 6.360.4578 1/4 -180.055560.488150.2278 4.100.1722 3.100.3389 6.100.6722 3/8 -180.055560.623540.240 4.320.1844 3.320.3511 6.320.6844 1/2 -140.071430.773970.320 4.480.2486 3.480.4629 6.480.8915 3/4 -140.071430.984410.339 4.750.2676 3.750.4819 6.750.91051 -11-1/20.08696 1.233200.400 4.600.3130 3.600.5739 6.60 1.09561-1/4 -11-1/20.08696 1.577950.420 4.830.3330 3.830.5939 6.83 1.11561-1/2 -11-1/20.08696 1.816910.420 4.830.3330 3.830.5939 6.83 1.11562 -11-1/20.08696 2.290840.436 5.010.3490 4.010.60997.01 1.13162-1/2 -80.12500 2.754350.682 5.460.5570 4.460.93207.46 1.68203 -80.125003.380690.7666.130.64105.131.01608.131.76608.Dryseal American Intermediate Internal Straight Pipe Thread (NPSI) For Assembly With Dryseal SAE Short External Taper (Table 3) or American Standard Taper Pipe Thread (Table 2)—Threads of this series are straight (cylindrical) instead of tapered. They are generally used in hard or brittle materials where the section is heavy and where there is little expansion at assembly with the external taper threads. These threads are primarily intended for assembly with PTF—SAE Short External Taper Threads, but will also assemble with full length NPTF External Taper Threads. Dimensional data for NPSI threads is given in T able 6. See Appendix D for limitations of assembly of NPSI internal threads with other series Dryseal pipe threads.TABLE 5—DRYSEAL AMERICAN STANDARD FUEL INTERNAL STRAIGHT PIPE THREAD LIMITS (1)1.See general specifications preceding tables.For gaging methods, gages, taps, drilled hole sizes, hole depths, and full thread lengths, see Appendixes A, B, and C.NPSF Size 1PitchDiameter(2)Max (3),(4)22.The pitch diameter of the tapped hole as indicated by the taper plug gage is slightly larger than the values given due to the gage having to enter approximately 3/8 turn to engage first full thread.3.Column 2 is the E 1 pitch diameter of thread at large end of internal thread (T able 2) plus (largel) 5/8 thread taper.4.Taps specified in T able B4 produce tapped holes to the above limits in cast iron, steel, and brass. In zinc and similar soft metals, they produce tapped holes approximately 0.001 smaller. Plug-gage turns engagement should be reduced accordingly.Pitch Diameter(2)Min (4),(5)35.Column 3 is Column 2 reduced by 1-1/2 turns.Minor Diameter (6)Min 46.As the Dryseal American Standard pipe thread form is maintained, the major and minor diameters of the internal thread vary with the pitch diameter.Desired MinLengthof Full Thread (7)in.57.Internal thread tabulated full thread lengths do not include countersink beyond the intersection of the pitch line and the chamfer cone (gaging reference point).Desired Min Length of Full Thread (7)Thread 6 1/16-270.28030.27680.24820.318.44 1/8 -270.37270.36920.34060.318.44 1/4 -180.49040.48520.44220.478.44 3/8 -180.62570.62050.57760.509.00 1/2 -140.77670.77000.71330.669.19 3/4 -140.98720.98050.92380.669.191 -11-1/21.23651.22841.16000.788.989.Notes9.1Marginal Indicia—The change bar (l) located in the left margin is for the convenience of the user in locating areas where technical revisions have been made to the previous issue of the report. An (R) symbol to the left of the document title indicates a complete revision of the report.PREPARED BY THE SAE SCREW THREADS COMMITTEETABLE 6—DRYSEAL AMERICAN INTERMEDIATE INTERNAL STRAIGHT PIPE THREAD LIMITS (1)1.See general specifications preceding tables.For gaging methods, gages, taps, drilled hole sizes, hole depths, and full thread lengths, see Appendixes A, B, and C.NPSF Size 1Pitch Diamete(2)Max (3),(4)22.The pitch diameter of the tapped hole as indicated by the taper plug gage is slightly larger than the values given due to the gage having to enter approximately 3/8 turn to engage first full thread.3.Column 2 is the same as the E 1 pitch diameter of thread at large end of internal thread (Table 2) minus (small) 3/8 thread taper.4.T aps specified in Table B5 produce tapped holes to the above limits in cast iron, steel, and brass. In zinc and similar soft metals, they produce tapped holes approximately 0.001 smaller. Plug-gage turns engagement should be reduced accordingly.Pitch Diameter (2)Min (3),(5)35.Column 3 is Column 2 reduced by 1-1/2 turns.MinorDiameter (6)Min 46.As the Dryseal American Standard pipe thread form is maintained, the major and minor diameters of the internal thread vary with the pitch diameter.Desired Min Length of Full Thread (7)in.57.Internal thread tabulated full thread lengths do not include countersink beyond the intersection of the pitch line and the chamfer cone (gaging reference point).Desired Min Length of Full Thread (7)Thread 71/16-270.28260.27910.25050.318.44 1/8 -270.37500.37150.34290.318.44 1/4 -180.49380.48860.44570.478.44 3/8 -180.62920.62400.58110.509.00 1/2 -140.78120.77450.71800.669.19 3/4 -140.99170.98500.92830.669.191 -11-1/2 1.24201.23381.16550.788.98APPENDIX ASUPPLEMENTARY THREAD INFORMATIONA.1Terminology—For definitions of terms relating to size of parts, geometrical elements, or dimensions of threads see SAE Standards Screw Threads, Appendix A—Terminology.A.2Dryseal American Standard And SAE Short External Taper Pipe Thread Blanks, Cut ThreadsFIGURE A1—A.2.1Formulas for Diameter and Length of Thread—Basic diameter and length of thread for different sizes givenin T ables 2, 3, and 4, are based on the following formulas:Basic pitch diameter of thread at small end of NPTF External Thread.(Eq. A1)Basic pitch diameter of thread at small end of PTF—SAE Short External Thread.(Eq. A2)Basic pitch diameter of thread at large end of NPTF Internal Thread.(Eq. A3)Basic pitch diameter of thread at large end of PTF—SAE Short Internal Thread.(Eq. A4)Basic length of NPTF external full and effective length thread.(Eq. A5)Basic length of PTF—SAE Short external full and effective length thread.(Eq. A6)Basic length of NPTF internal full and effective length thread = L 1 Basic + L 3E 0D 0.05D 1.1)p+(–=E 0Short D 0.05D 1.037)p+(–=E 1E 00.0625XL 1 Basic )(+=E 1Short E 00.0625XL 1 Short )(+=L 20.8D 6.8)p+(=L 2Short 0.8D 5.8)p+(=Basic length of PTF—SAE Short internal full and effective length thread = L 1 Short + L 3WhereD = outside of diameter of pipe P = pitch of thread in inchesNPSG (for oil and grease cup) is Dryseal American Standard Pipe Thread Form—use NPSF tap drill sizes.The drilled hole sizes given above for Dryseal straight and taper internal pipe threads are the diameters produced by drills which are closest to the minimum minor diameters as shown in Table A2.They represent the diameters of the holes which would be cut with a twist drill correctly ground when drilling a material without tearing or flow of metal. This is approximately the condition obtained when a correctly sharpened twist drill is cutting a hole in SAE 1112 or 1113 steel, or SAE 72 brass. When Dryseal taps are used, these holes produce an acceptable pipe thread with the required thread height.When flat drills are used, the width of the cutting edge may have to be adjusted to produce a hole of the required diameter.When hard metals and other similar materials are to be drilled and tapped, it may be found necessary to use a drill of slightly smaller diameter to produce a hole of a size that will make it possible for the tap to cut an acceptable pipe thread with the required thread height.When soft metals and other similar materials are to be drilled and tapped, it may be found necessary to use a drill of slightly larger diameter to produce a hole of a size that will allow for a flow of the metal or material without loading the tap or tearing the material and make it possible for the tap to produce an acceptable pipe thread with the required thread height.TABLE A1—DIMENSIONS OF DRYSEAL AMERICAN STANDARD EXTERNALTAPER PIPE THREAD BLANKS (CUT THREADS)Size OD at Large End NPTF at L 2 Length D 2PTF—SAE Short at L 2 - 1/2p Length (Basic Thread One Turn Large with Max Truncation)+0.003 - 0.000OD at Small End, A NPTF(Basic Thread Two Turns Large with Max Truncation)+0.003 - 0.000OD at Small End, APTF-SAE Short (Basic Thread 2-1/2 Turns Lare with MaxTruncation)+0.003 - 0.000Chamfer Dia (1), B (Minor Dia (1) atSmall End)1.External pipe threads shall be chamfered from a diameter (rounded to a two-place decimal) obtained by subtracting 0, .016 in. for sizesbelow 1 in. and 0.025 in. for larger sizes from the minimum minor diameter at small end to produce a length of chamfered or partial thread equivalent to 1 to 1-1.2 times the pitch (rounded to a three-place decimal).Min Length fromSmall End to Shoulder, TLNPTFL 2 + (3p Approx)Min Length from Small End to Shoulder, TLPTF-SAE ShortL 2 Short + (2-1/2pApprox)Corner Radius, R Max RecommendedHole Size (2), H2.The hole sizes recommended respresent a desirable maximum, strength of wall being considered. However, as considerations otherthan wall strength frequently control the hole size in specific applications, the recommendations should not be construed as a require-ment of this SAE Standard.1/16-270.3150.3010.3020.230.380.31670.030.12 1/8 -270.4070.3930.3940.320.380.31940.030.19 1/4 -180.5460.5230.5250.42 +0.000.560.48510.060.28 3/8 -180.6810.6580.6600.550.560.49110.060.41 1/2 -140.8500.8200.8220.68 -0.020.750.64090.080.56 3/4 -14 1.060 1.029 1.0310.890.750.65280.080.721 -11-1/2 1.327 1.289 1.292 1.120.940.81320.090.941-1/4 -11-1/2 1.672 1.633 1.636 1.46 +0.000.970.83720.09 1.251-1/2 -11-1/2 1.912 1.872 1.875 1.70 1.000.85390.09 1.472 -11-1/2 2.387 2.345 2.348 2.17 -0.03 1.030.88690.09 1.942-1/2 -8 2.893 2.829 2.833 2.59 1.52 1.32500.12 2.313 -83.5183.4503.4543.211.581.38750.122.91A.3Pipe-Thread Drilled Hole Sizes For Dryseal American Standard Internal Pipe Thread—It should be under-stood that this table of drilled hole sizes is intended to help only the occasional user of drills in the application of this SAE Standard. When internal pipe threads are produced in larger quantities in a particular type of material and with specially designed machinery, it may be found to be more advantageous to use a drilled hole size not given in the table, even one requiring a nonstandard diameter drill size.TABLE A2—PIPE-THREAD DRILLED HOLE SIZESSize Straight Pipe Thread Fuel (NPSF)MinorDia (1)Min 1.Minimum minor diameter for internal straight pipe threads is based upon minimum pitch diameter and minimum truncation and will varywith the pitch diameter.Straight Pipe Thread Fuel (NPSF)Drilled Hole Size +0.003-0.001Straight Pipe Thread Intermediate (NPSI)Minor Dia (2)Min2.NPTF (taper reamed) drilled hole sizes are recommended for taper reaming before tapping. They also are used without taper reaming by taper drilling or allowing the tap to act as a reamer. Thread lengths so produced are designated "Full or Complete Thread" on drawings.Straight PipeThreadIntermediate (NPSI)Drilled Hole Size+0.003-0.001Straight PipeThread DesiredLength of Full Thread Min Straight Pipe Thread Hole Depth for Plug End Tap, Tables B4 and B5Taper Pipe Thread NPTF (Not Reamed)2 FF Thread (3)Minor Dia 2 Thread Small from Large EndMin 3.NPTF (not reamed) drilled hole sizes are recommended for taper tapping without reaming. [NPTF (2 FF thread)] minimum minor diameter two threads small from large end and closest drilled hole sizes are recommended only for low pressure use. [NPTF (4 FF thread)] mini-mum minor diameter four threads small from large end and closest drilled hole sizes are recommended for all pressures. Thread lengths so produced are designated "Effective Thread" on drawings.Taper Pipe Thread NPTF (Not Reamed)2 FFThread (2)Drilled Hole Size+0.003=0.001Taper Pipe Thread NPTF (Not Reamed)4 FFThread (2)Minor Dia4Thread Small from Large End Min Taper Pipe Thread NPTF (Not Reamed)4 FFThread (2)DrilledHole Size +0.003-0.001Taper Pipe Thread NPTF (4)(TaperReamed)Desired Minor Dia at Small End Min 4.Internal pipe threads shall be countersunk 90 deg included angle to a diameter (rounded to a two-place decimal) obtained by adding 0.016 in. for sizes below 1 in. and 0.025 in. for larger sizes to the maximum major diamter at large end.Taper PipeThread NPTF (4)(TaperReamed)DrilledHole Size +0.003-0.001Taper Pipe Thread Desired Length ofFull Thread Min Taper Pipe Thread Hole Depth for Standard Tap, Table B2Countersink 90 Deg x dia (4)1/16-270.24820.25000.25050.25000.310.470.24800.24600.24340.24200.23560.23440.310.560.33 1/8 -270.34060.34370.34290.34370.310.470.34030.33900.33570.33200.32790.32810.310.560.42 1/4 -180.44220.44400.44570.44400.470.720.44170.43750.43480.43000.42410.42190.470.810.55 3/8 -180.57760.57810.58110.57810.500.720.57710.57810.57020.57000.55870.56250.500.810.69 +0.021/2 -140.71330.71870.71800.71870.660.940.71270.70310.70380.69600.68730.68750.66 1.060.85 -0.00 3/4 -140.9238—0.9283—0.660.940.92320.92190.91430.90620.89760.89060.66 1.06 1.061 -11-1/2 1.1600— 1.1655—0.78 1.16 1.1593 1.1562 1.1484 1.1406 1.1290 1.12500.78 1.25 1.341-1/4 -11-1/2——————1.50411.50001.49321.48441.47251.46870.811.311.68+0.031-1/2 -11-1/2—————— 1.7430 1.7344 1.7321 1.7188 1.7115 1.70310.81 1.31 1.922 -11-1/2—————— 2.2170 2.2187 2.2061 2.2031 2.1844 2.18750.81 1.31 2.39 -0.002-1/2 -8—————— 2.6488 2.6406 2.6336 2.6250 2.5983 2.5937 1.25 1.84 2.893 -8——————3.27513.26563.25953.25003.21943.21871.341.913.52。
干了十几年液压，今天才明白锥管螺纹代号NPT，NPSC，NPTF的含义
干了十几年液压，今天才明白锥管螺纹代号NPT，NPSC，NPTF的含义展开全文Hydoon在设计过程中经常遇到不同标注的管螺纹，有PT的，NPT的，还有Rc的，有时候被这些代号搞得一头雾水，而且还很容易弄错，甚至出现不匹配的现象，直到今天才真正搞清楚这些代号的含义。
机械财经将分期给大家介绍，今天介绍NPT， NPSC和NPTF。
1NPT美制管螺纹以60°牙型为主，也有很多种类，我们不一一介绍，只介绍最常见NPT，NPTF和NPSC美国的图纸上经常会看到类似NPT 3/8的标记。
其中NPT 是National (American) Pipe Thread 的一种，NPT表示锥螺纹，代表英文Taper pipe thread for general purpose，这属于美国标准的60 度锥管螺纹, 锥度为1:16，是一种密封管螺纹，使用这种连接时候无需增加密封措施。
其中3/8并不是说螺纹直径为3/8英寸，而是一个尺寸代号，还要去查找标准才能知道大径，小径的尺寸，不过这并不影响工程师绘图，只要在液压管路或接头的图纸标注3/8即可，制造厂家会根据标准生产。
有时还会有数字后缀，如3/8-18，18代表一英寸的内的牙数，这个可以不标记。
有时会看到还有尾部字母LH，代表的是左旋螺纹，left-hand。
无标记默认是右旋螺纹。
2NPSC外锥螺纹可以和内锥螺纹配合，具有密封作用，但是美标中还有一种密封直螺纹，就是NPSC，是Nation Pipe strain connection的缩写，一种管接头直管内螺纹Internal straight pipe thread for connection。
在实际中这种内螺纹是可以和外锥螺纹的接头配合使用的。
那么，就存在了两配合，外锥-内锥，外锥- 内直。
两种配合形式本身具有密封性，同时都允许在螺纹中添加密封材料，实际应用中也都会增加填充物来密封，如密封胶。
3NPTF然后再说，NPTF，NPTF是干密封直管螺纹Dryseal straight pipe internal thread的代号，其中的F应该是代表 Fine的意思。
FNPT与NPT与MNPT与NPTF与3_8_18NPT
FNPT与NPT与MNPT与NPTF与3/8-18NPT NPT 是National (American) Pipe Thread 的缩写，属于美国标准的60 度锥管螺纹。
NPT螺纹分：一般密封圆柱管螺纹和一般密封圆锥管螺纹二、基本尺寸：螺纹中径尺寸D2=d2=D-0.8*P螺纹小径尺寸D1=d1=D-1.6*PFNPT为内螺纹，还有个MNPT，它是外螺纹。
N.P.T为美国螺纹标准。
NPT是美标锥管螺纹National Pipe Thread的英文缩写，与国标的ZG（现在也改为NPT了）是一样的；NPTF（或者FNPT）通常指NPT的内螺纹，也就是National Pipe Thread Female;NPTM通常指NPT的外螺纹，也就是Nat ional Pipe Thread Male。
严格的说,NPTF指的是美制干密封圆锥管螺纹,牙形角60度,斜度1度47分,NP T为美制一般密封圆锥管螺纹也有通俗的说：MNPT表示阳管螺纹，FNPT表示阴管螺纹。
3/8NPT与3/8-18NPT区别3/8指的是3/8英寸（内径），也就是俗称的“三分”。
3/8：指的是3/8英寸（内径），也就是俗称的“三分”。
-18：是指每英寸螺纹牙数为18.由此也可以确定螺距为25.4/18=1.41mm。
npt3/8是60度牙形角的英制管螺纹；r3/8是55度牙形角的英制管螺纹的外螺纹。
管螺纹主要用来进行管道的连接，其内外螺纹的配合紧密，有直管与锥管两种。
公称直径是指所连接的管道直径，显然螺纹大径比公称直径大。
外螺纹是只在圆柱或者圆锥外表面的螺纹。
例如螺栓表面的螺纹即为外螺纹，而螺母的螺纹为内螺纹。
英制螺纹是螺纹尺寸用英制标注，按外形分圆柱、圆锥两种；按牙型角分55°、60°两种。
NPT一般用于管螺纹，NPT 是National (American) Pipe Thread 的缩写，属于美国标准的60度锥管螺纹，用于北美地区。
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NPT，PT，G都是管螺纹．NPT 是National (American) Pipe Thread 的缩写，属于美国标准的60 度锥管螺纹，用于北美地区．国家标准可查阅GB/T12716-1991PT 是Pipe Thread 的缩写，是55 度密封圆锥管螺纹，属惠氏螺纹家族，多用于欧洲及英联邦国家．常用于水及煤气管行业，锥度规定为1:16．国家标准可查阅GB/T7306-2000G 是55 度非螺纹密封管螺纹，属惠氏螺纹家族．标记为G 代表圆柱螺纹．国家标准可查阅GB/T7307-2001另外螺纹中的1/4、1/2、1/8 标记是指螺纹尺寸的直径，单位是英吋．行内人通常用分来称呼螺纹尺寸，一吋等于８分，1/4 吋就是２分，如此类推．G 就是管螺纹的统称(Guan)，55，60度的划分属于功能性的，俗称管圆。
即螺纹由一圆柱面加工而成。
ZG俗称管锥，即螺纹由一圆锥面加工而成，一般的水管接头都是这样的，国标标注为Rc公制螺纹用螺距来表示，美英制螺纹用每英寸内的螺纹牙数来表示，这是它们最大的区别，公制螺纹是60度等边牙型，英制螺纹是等腰55度牙型，美制螺纹60度。
公制螺纹用公制单位，美英制螺纹用英制单位。
管螺纹主要用来进行管道的连接，其内外螺纹的配合紧密，有直管与锥管两种。
公称直径是指所连接的管道直径，显然螺纹直径比公称直径大。
1/4，1/2，1/8是英制螺纹的公称直径，单位是英寸。
、从设计角度来说，螺纹副旋合后，在基面距内应形成无隙结合。
实际上各直径、牙型角、螺距和锥角在制造中都有偏差。
NPT螺纹的牙顶和牙底为过渡配合，仅靠板紧螺纹副时的微量变形来达到100%的无隙量是不可能的。
为了确保其密封性能，往往需要螺纹副内加一定的密封介质，它主要适应于中低压系统。
NPTF螺纹的牙顶和牙底为过盈配合，扳紧螺纹副后，窄平的牙底迫使尖的牙顶弹塑性变形，因而获得100%的过盈配合，无需密封介质即能阻止泄漏，适于高压系统大径、小径不同NPTF螺纹与NPT螺纹的螺距P、基面距L1、基面上的中径d2均相同，大径、小径的计算方法也相同，但因两者牙高不同，所以大径小径并不相同。
以东方红LF拖拉机上1/ 2－14 NPTF标准快换接头座螺纹为例：已知：P=1.814 mm,L1=8.13 mm,d2=19.772 mm,若按NPT螺纹计算，则基面上d大径=d2+0.8P=21.223 mmd小径=d2-0.8P=18.321 mm按照NPTF螺纹计算，则基面上d大径=d2+0.746P=21.125 mmd小径=d2-0.746P=18.419 mm由此看出，两者的大小径是有区别的。
螺纹代号Thread Code一、英制螺纹（螺纹牙型角55度）Thread of British standard ( Thread pitch sh ape angle 55°)BSW－－－－英国标准惠氏螺纹（粗牙）British Standard Whitworth Thread ( C oarse )BSF－－－－英国标准惠氏螺纹（细牙）British Standard Whitworth Thread ( Fi ne )G－－－－直管螺纹（外螺纹分A、B两面级、丝锥分G、G－D）Straight pipe thr ead ( Outside )thread in A\B: taps in G、G－D )R－－－－锥管外螺纹（旧代号ZG;KG）Outside paper pipe thread ( Old thread code ZG,KG )RC－－－－锥管内螺纹（旧代号ZG;KG）Inside taper pipe thread ( Old thread code ZG,KG )二、美制螺纹（螺纹牙型角60度）Thread of American standard ( Thread pitch shape angle 60°UNC－－－－统一制粗牙螺纹（代替NC）Unified coarse pitch thread ( Instead of NC )UNF－－－－统一制细牙螺纹（代替NF）Unified fine pitch thread ( Instead of NF )UNEF－－－－统一制超细牙螺纹Unified superfine pitch threadUN－－－－－统一制不变螺距螺纹Unified threadUNS－－－－统一制特殊螺纹Unified Special threadNPT－－－－一般用途锥管螺纹（旧代号Z;K）Taper pipe thread for general pur pose ( Oldthread code Z,K )NPSC－－－－管接头直管内螺纹Internal straight pipe thread for connectionNPSM－－－－设备上自由配合，机械连接用直管螺纹Straight pipe thread for ge neral purposeNPTF－－－－干密封锥管螺纹Dryseal taper pipe threadNPSF－－－－干密封燃油直管螺纹Dryseal straight pipe internal threadNGT－－－－气瓶用锥螺纹Special thread for gas cylinder三、米制螺纹Metric threadZM－－－－－米制锥管螺纹Metric taper pipe thread四、其它螺纹Other threadsSM－－－－缝纫机螺纹Thread for sewing machinePZ－－－－气瓶用锥螺纹Special thread for gas cylinder5V1－20V1－气门芯螺纹5V1－20V1－Tyre valve thread螺纹代号说明示例：Explanation of thread code. e. g.1/4－20UNC1/4－公称直径1/4" nominal dia. 1/4"20－每寸20牙twenty teeth per inchUNC－美标统一制粗牙螺纹unified coarse pitch thread ( American standard谈谈美制密封锥管外螺纹的代号有哪些美制密封锥管外螺纹的代号:NPT,NPTFNPT代表美国标准管螺纹(National Pipe Tapered) ，NPTF则是干密封式美国标准管螺纹。
两者基本牙型是一样的，不同点是：螺纹牙高不一样。
NPT可能有过盈也可能有间隙，但NPTF没有间隙；NPT内外螺纹均为圆锥，而NPTF外螺纹是圆锥，内螺纹则有圆锥、圆柱两种；NPT有右旋也有左旋，NPTF只有右旋一种旋向。
RC 是英制密封内螺纹代号,R是英制密封外螺纹代号,NPT是美制密封螺纹代号NPT是密封圆锥管螺纹。
NPSC是密封圆柱内螺纹。
NPT是美标锥形密封螺纹密封性差一点NPTF是美标锥形干密封螺纹二者差异很小，精度等级要高很多，一般不用。
NPT和NPTF螺纹是两种美国最常用的锥管螺纹。
应用范围从电线管道和扶手到运送煤气或腐蚀性液体的高压管线。
NPT用于机械的或者低压的气体和液体，要求使用密封剂来保证密封。
当密封要求严格时，密封剂可能由于高温高压会失效，这时可以采用NPTF干密封螺纹。
当用扳手上紧配件时，这种机械密封会在螺纹配合和轻微的变形来生成密封效果。
这两种螺纹在目测时是相同的。
两种在一英尺的长度上都有3/4的锥度。
在内螺纹的孔的顶端或者外螺纹的管的端部拥有相同的中径，而且拥有相同的螺纹长度和深度。
尽管如此，在螺纹牙型上还是有细微的差别。
两螺纹的大直径和小直径上有细微的差别。
对于NPT螺纹，使用扳手上紧后，在大直径和小直径上可能允许装配后漏气，因此会使用密封剂来填充所有的间隙。
另一方面，NPTF螺纹的设计用于保证在整个牙形上产生足够的变形以生成这种机械密封。
牙型的不同如何影响使用的工具来生产NPT和NPTF螺纹？NPT和NPTF螺纹牙形都是采用丝锥来生产每种螺纹。
因为NPT螺纹零件要求密封剂，用NPTF丝锥在攻NPT螺纹是可以接受的。
但是NPT丝锥不能用于NPTF螺纹，因为它生产的螺纹会漏气。
最大的不同是这两种螺纹的检查要求。
因为NPT螺纹要使用密封剂，只要用一个塞规，大家叫L1规（内螺纹）或L1环规（外螺纹）来检查尺寸。
但是，因为锥度和大直径，小直径对NPTF螺纹的密封很重要，因此要求其他的螺纹验规L2和L3规，大直径和小直径要用特殊的塞规或环规来检验。
密封式锥管螺纹量规NPTF2007年末季，我省的螺纹出口企业的NPTF、NPT螺纹产品质量出现问题，引起了我院的高度重视。
我院对其送检的螺纹量规进行检测，结果发现，国内螺纹量规生产厂家生产的NPTF量规、NPT量规，干密封式锥管螺纹NPTF-L1塞规的大径、NPTF-L1环规的小径、普通锥管螺纹NPT量规（实际应为NPT-L1）中螺距为每英寸27牙及每英寸18牙的塞规大径、环规的小径，与美国、英国、德国、日本等国家生产的量规相比不同。
经多方了解，原来国内的螺纹量规生产厂家生产干密封式锥管螺纹NPTF工作量规，普遍采用的是FED-STD-H28/8（1978）标准，美国、英国、德国、日本等国家采用的是ASME B1.20.5-1991标准；生产普通锥管螺纹NPT工作量规，国内普遍采用的是FED-STD-H28/7（1978）标准，美国、英国、德国、日本等国家采用的是ASME B1.20.1-1983标准。
实际上FED-STD-H28/8B（2001）标准中对NPTF 量规的技术要求与ASME B1.20.5-1991标准一致；FED-STD-H28/7A（2001）标准中对NPT量规的技术要求与ASME B1.20.5-1983标准一致。
FED-STD-H28/8（1978）标准与ASME B1.20.5-1991标准相比，其主要不同点是：FED-STD-H28/8（1978）标准规定NPTF工作量规牙顶削平量为0.2P~0.25P； ASME B1.20.5-1991标准中NPTF工作量规L3螺纹塞规和L2螺纹环规的牙顶削平量为0.2P，但L1螺纹量规的牙顶削平量等于螺纹产品牙底的最大削平量，根据ANSI B1.20.3-1976标准可查得，每英寸27牙的螺纹量规牙顶削平量为0.140P，每英寸18牙的螺纹量规牙顶削平量为0.109P，每英寸14牙的螺纹量规牙顶削平量为0.085P，每英寸11 1/2牙的螺纹量规牙顶削平量为0.090P，每英寸8牙的螺纹量规牙顶削平量为0.076P。
因此，采用FED-STD-H28/8（1978）标准生产的L1螺纹塞规的大径比ASME B1.20.5-1991标准中的标准值小，L1螺纹环规的小径比ASME B1.20.5-1991标准中的标准值大。