37 is the number one resource for everything you need to know about Threaded Gages and is a great reference guide for any shop or laboratory. The confusion generates questions and assumptions. This defines a series of metric screws named after their major diameters in millimetres, from 0.30 UNM to 1.40 UNM. The Unified Thread Standard (UTS) defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada. The minor diameter Dmin and effective pitch diameter Dp are derived from the major diameter and pitch as. 27AAOFG2045B1ZP. It also establishes the criteria for screw thread acceptance when a gauging system is used. Pipe Gages per ASME B1.20.1,  ASME B1.20.5 and Hole Location gages stocked. It conforms to ANSI/ASME B1.1 standard Manufacturing Range : Thread Plug & Ring Gauges from No.4 (0.112”) to 10” Working Thread Plug, Thread Ring and Thread Setting Plug Gages are manufactured to inspect the Pitch Diameter and the Functional Thread. Class 1 threads are loose fit, intended for ease of assembly or use in a dirty environment. To calculate the major diameter of "aught" size screws count the number of extra zeroes and multiply this number by 0.013 in and subtract from 0.060 in. UTS threads do not usually use the pitch parameter; instead a parameter known as threads per inch (TPI) is used, which is the reciprocal of the pitch. Locate a Vermont Gage Distributor in your area. Lower cost than similar gages from competitors. [4][5] Most UNS threads have more threads per inch than the correlating UNF or UNEF standard; therefore they are often the strongest thread available. Send Email. Unified Inch Screw Threads. M Series Metric thread gages are manufactured per ASME B1.16M. Compatiable with screw thread inserts from Helicoil, Recoil and others. We are among the leading manufacturers of Unified Thread Gauges in the industry. Conversely, in an internal (female) thread (e.g., in a nut), the major and minor diameters are minimum dimensions, therefore the thread profile must end flat at Dmin but may be rounded out beyond Dmaj. Preferred sizes are 0.3, 0.4, 0.5, 0.6, 0.8, 1.0 and 1.2 mm, with additional defined sizes halfway between. Get answers to your gaging and GAGE CLEANING questions, ©2021 Vermont Gage All Rights Reserved. Our gauges are used in several big companies and are in great demand across country. It is the main standard for bolts, nuts, and a wide variety of other threaded fasteners used in these countries. 1 0.073 64 72 - - No. The most common method used in production is by way of a go/no-go gauge. Unified Miniature Thread Plug Gages: WESTport Gage provides a full range of Unified Miniature Screw Thread Plug Gages per the American Standard B1.10M 2004 and the equivalent ISO Recommendation. Available in 3B or 2B (Unified); 4H or 5H (Metric) Class of Fit. standards British Standard 1580 Unified (ISO, inch) screw threads: Parts 1 and 2 (1962); Part 3 (1965). Unified Thread Gauges Unified Threads are used for general purpose fastening applications for Imperial system of units. In the plane of the thread axis, the flanks of the V have an angle of 60° to each other. These gauges are offered in standard style and also as … In an external (male) thread (e.g., on a bolt), the major diameter Dmaj and the minor diameter Dmin define maximum dimensions of the thread. Unfied Gauges Basic Dimensions as per BS 1580 Part 1 & 2 - 2007 & Gauging Practice as per BS 919 Part 1-2007 are manufactured if requested by customers. When this Standard is approved by the Department of Defense and federal agencies and is incorporated into Federal Standard-H28/20 [FED-STD-H28/20], Screw Thread Standards for Federal Services, Section 20, the use of this Standard by the federal government is subject to all the requirements and limitations of Federal Standard-H28/20 [FED-STD-H28/20]. The following formula is used to calculate the major diameter of a numbered screw greater than or equal to 0: Major diameter = Screw # × 0.013 in + 0.060 in. Unified Thread Gauge - Thread Ring Gauge dimensions as per ANSI / ASME B1.2. If the fastener turns on the gauge smoothly with no binding, the user will know it is falls within the specific tolerance. Example: #6-32 UNC 2B (major diameter: 0.1380 inch, pitch: 32 tpi). Grainger's got your back. Unified Inch standard gages are manufactured per ASME B1.2. In the Unified Thread Standard (UTS) system, manufacturers list the diameter size as a number between 0 and 10, with 0 being the smallest and 10 being the largest. Threaded plug gauges, also called thread plug gauges, thread gauges, or simply plugs, are used to check and inspect internal threads by attempting to mate the Go and No-Go gauge members to the threaded part. GST No. Screws larger than a #10 have a diameter listed directly in inches. Product Description Widely used for the purpose of measuring the pitch or lead of a screw thread in several industries, this Unified Thread Gauges is quite asked for. Currently this gauging for UTS is controlled by: This Standard provides essential specifications and dimensions for the gauges used on Unified inch screw threads UN [unified] and UNR [external threads only] thread form, and covers the specifications and dimensions for the thread gauges and measuring equipment listed in Tables 1 and 2. It has a diameter of 0.112 in (0.28 cm). Each thread in the series is characterized by its major diameter Dmaj and its pitch, P. UTS threads consist of a symmetric V-shaped thread. For example, the major diameter of a 0000 screw thread is 0.060 in − (3 × 0.013 in) = 0.060 in − 0.039 in = 0.021 in. The thread form is slightly modified to increase the minor diameter, and thus the strength of screws and taps. The relationship between the height H and the pitch P is found using the following equation where Gages and Gaging for Unified Inch Screw Threads. Call 08041948412 86% Response Rate . Screw Thread Gaging Systems for Dimensional Acceptability – Inch and Metric Threads (UN, UNR, UNJ, M and MJ). [2]:1858–1859 This increases the amount of the theoretical sharp V which is cut off at the minor diameter by 10% from 0.25H to 7/8 − 0.52/cos 30° ≈ 0.27456H. The Unified Thread Standard (UTS) defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada. Galaxy Tools International. (pdf) We certify our gages to meet or exceed all published specifications and are […] Thread Gauges We are one of the most efficient manufacturers and suppliers of Thread Gauge. Class 2 threads are free fit, and the most common. There are several methods that are used to measure the pitch diameter. Distributed by: Gage Crib Worldwide Inc 6701 Old 28th St SE, Suite B Grand Rapids, MI 49546-6937 USA In the Unified National Series the ½ inch size has 13 threads per inch, but the American Standard was 12 threads per inch. These standards provide essential specifications and dimensions for the gauges used on Unified inch screw threads (UN, UNR, UNJ thread form) on externally and internally threaded products. Some find the requirements confusing. Unified Theads. Unified Inch standard gages are manufactured per ASME B1.2. [6] Because of this they are often used in applications where high stresses are encountered, such as machine tool spindles[7] or automotive spindles.[8]. Choose from our selection of thread gauges, including size identifying, size checking, and more. The basic purpose and use of each gauge are also described. The offered gauges are extensively utilized for fastening applications and are made available in coarse, fine, and extra fine variants. θ Wholesale Trader of Thread Ring Gauge - Unified Thread Gauge offered by Galaxy Tools International, Mumbai, Maharashtra. Unified Threads are used for general purpose fastening applications for Imperial system of units. We are the Special Thread Gauge suppliers and manufacturers in India. The pitch P is the distance between thread peaks. [2]:1861 The standard thread pitch is approximately .mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px;white-space:nowrap}1/4 of the major diameter. M Series Metric thread gages are manufactured per ASME B1.16M. The UTS is currently controlled by ASME/ANSI in the United States. 50 Years of quality products and services. Most (but certainly not all) threaded items are made to a classification standard called the Unified Screw Thread Standard Series. BS 1580: Pt1: 2007 specifies details of product threads. Unified Gauges Basic Dimensions as per BS 1580 part 1 & 2-2007 & Gauging Practice as per BS 919 Part 1 -2007 are manufactured if requested by customers. It has the same 60° profile as the ISO metric screw thread, but the characteristic dimensions of each UTS thread (outer diameter and pitch) were chosen as an inch fraction rather than a millimeter value. ACME, Buttress, STI and gages for other custom thread forms are also available. Vermont inch gages have light blue handles to help avoid confusion with metric gages … We manufacture this product using quality raw materials and advanced technology, in order to provide quality goods to our clients. The number series of machine screws once included more odd numbers and went up to #16 or more. We manufacture this product using quality raw materials and advanced technology, in order to provide quality goods to our clients. Easy online ordering for the ones who get it done along with 24/7 customer service, free technical support & more. Specifications : ANSI/ ASME B1.2-1983 Unified Gauges Basic Dimensions as per BS 1580 part 1 & 2-2007 & Gauging Practice as per BS 919 Part 1 -2007 are manufactured if requested by customers. It establishes the criteria for screw thread acceptance when a gauging system is used. Why am I unable to order a class “6H” “M” series metric thread ring gage? Class 4 threads previously designated a close fit for even tighter tolerances, but this classification is now obsolete. (b) A screw thread gauging system comprises a list of screw thread characteristics that must be inspected to establish the dimensional acceptability of the screw threads on a threaded product and the gauge(s) which shall be used when inspecting those characteristics. Unified Threads are used for general purpose fastening applications for Imperial system of units. The offered gauges are extensively utilized for fastening applications and are made available in coarse, fine, and extra fine variants. 0 0.06 - 80 - - No. Standard thread gages are made to a Class X tolerance. In the Unified National Series the ½ inch size has 13 threads per inch, but the American Standard was 12 threads per inch. UNIFIED Thread Gauges Unified Threads are used for general purpose fastening applications for Imperial system of units. For example, a number 10 calculates as: #10 × 0.013 in + 0.060 in = 0.190 in major diameter. For example: A 3-48 thread means the thread is 3 gauge (0.099 inch major diameter) and has 48 threads per inch. in Inch UNC UNF UNEF UN No. A classification system exists for ease of manufacture and interchangeability of fabricated threaded items. Ensures accuracy of the finished threads. Gauges for testing Unified threads to BS 1580: Parts 1&2:2007, BS 1580: Part 3: 2007, and BS 919: Part 1: 2007. Classes 1A, 2A, 3A apply to external threads; Classes 1B, 2B, 3B apply to internal threads.[9]. American Unified threads (UNC, UNF) and metric threads are defined by two dimensions, the thread size and the thread pitch. Metric gages are tools for measuring and quality checks in metric dimensions. The basic purpose and use of each gauge are also described. is half the included angle of the thread, in this case 30 degrees:[1]. Available for a full range of Unified and Metric thread sizes. ASME/ANSI B1.1 – 2019 Unified Inch Screw Threads, UN, UNR, & UNJ Thread Form, ASME/ANSI B1.10M – 2004 Unified Miniature Screw Threads, This page was last edited on 14 January 2021, at 22:12. Unified Thread Gauge - Thread gauge dimensions as per ANSI / ASME B1.2. Special Thread Gauge suppliers and manufacturers in India Now, it is less common to see machine screws larger than #14, or odd number sizes other than #1, #3 and #5. For example, on a #4-40 UNC-3A x.5 screw, #4 represents the diameter. The standard designation for a UTS thread is a number indicating the nominal (major) diameter of the thread, followed by the pitch measured in threads per inch. UN thread calculator covers: - UN and UNR thread forms The thread pitch for an American National Standard Unified 60 ° thread is: E = M + 0.86603P – 3W Notice that if we know the pitch (P) and the wire diameter (W), then for … Price $59.85. The major diameter still extends to within 1/8H of the theoretical sharp V, but the total depth of the thread is reduced 4% from 5/8H = 5/8 cos(30°) P ≈ 0.541P to 0.52P. Narayan Dhuru Cross Lane, Mumbai, Maharashtra. For diameters smaller than ​1⁄4 inch, the diameter is indicated by an integer number defined in the standard; for all other diameters, the inch figure is given. Even though #14 and #16 screws are still available, they are not as common as sizes #0 through #12. This system is analogous to the fits used with assembled parts. UNIFIED (UN) thread gauges: Other types of gauges: Gas (G) thread gauges: Limit plug gauges, setting rings: BSW / BSF / Whitworth gauges: Master check gauges: ACME / STUB ACME gauges: Wear check gauges: Thread gauges: 1. 3 0.099 48 56 - - No. In addition to Unified Inch Screw Thread standards, we offer our full range of stock gages in sizes that conform to metric standards. 2 0.086 56 64 - - No. ASME UN screw thread calculator to calculate imperial unified screw thread basic major, minor, pitch diameters and thread tolerance for the external (bolt) and internal (nut) inch threads according to ASME B1.1 standard. For UTS threads, which are single-start threads, it is equal to the lead, the axial distance that the screw advances during a 360° rotation. PMC Mercury Precision Measuring Tools Handbook No. Characterized by high precision, these Looking for MITUTOYO Thread Pitch Gauge Set, Thread Type Unified Inch, Number of Leaves 51 (1ZRV1)? The outermost ​1⁄8 and the innermost ​1⁄4 of the height H of the V-shape are cut off from the profile. |, Website Design & Development by Bluehouse Group. If “2A” is for an external thread, why does it apply to the thread setting plug? {\displaystyle \theta } We are among the leading manufacturers of Unified Thread Gauges in the industry. Unified threads use nominal gauge sizes for the thread diameter and threads-per-inch (TPI) for the thread pitch. Specification • ANSI/ASME B 1.2-1983. (a) This Standard presents screw thread gauging systems suitable for determining the acceptability of Unified [UN], UNR [external threads only], UNJ [internal and external threads], M, and MJ screw threads on externally and internally threaded products. t. ASME B1.3M ASME B1.3M Œ . t. ASME B1.2 ASME B1.2 Œ . Total Solution for Thread Gauging 07 UNIFIED THREADS Dia Dia. It is the main standard for bolts, nuts, and a wide variety of other threaded fasteners used in these countries. In stock and ready to ship. Gages may be purchased individually or as assemblies. Home: Profile: (c) Federal Government Use. harvnb error: no target: CITEREFObergJonesHortonRyffel2000 (, "History of standardization" section of the screw thread article, Unified Coarse/Fine diameters and tap drill sizes, Imperial Metric fastening size conversion charts, Conversion chart Whitworth/BSF/AF and metric, ASME B1.1-2003 Unified Inch Screw Threads, (UN and UNR Thread Form), https://en.wikipedia.org/w/index.php?title=Unified_Thread_Standard&oldid=1000389682, Articles with unsourced statements from December 2009, Creative Commons Attribution-ShareAlike License, ASME/ANSI B1.2-1983 Gauges And Gauging For Unified Inch Screw Threads, ASME/ANSI B1.3-2007 Screw Thread Gauging Systems for Acceptability: Inch and Metric Screw Threads (UN, UNR, UNJ, M, and MJ). The number series of machine screws has been extended downward to include #00-90 (0.047 in = 0.060 in − 0.013 in) and #000-120 (0.034 in = 0.060 in − 2 × 0.013 in) screws;[3] however, the main standard for screws smaller than #0 is ANSI/ASME standard B1.10 Unified Miniature Screw Threads. Because of this UNS taps are readily available. UNS threads are rarely used for bolts, but rather on nuts, tapped holes, and threaded ODs. Thread Plug Gauges are available with Dia range 1.3 to 210 mm and Thread Ring Gauges are available with Dia range 1.3 to 200 mm. Product Description Widely used for the purpose of measuring the pitch or lead of a screw thread in several industries, this Unified Thread Gauges is quite asked for. Class 3 threads are medium fit, still quite common and used for closer tolerances on high quality work. Thread gages are used to ensure the assembly of mating parts. Search. They are designed to maximize strength considering typical machine shop capability and machine practice. This thread designation is also referred to as the UNM Series. UNIFIED THREAD GAUGES . UNIFIED THREAD PROFILE Gauge Type Diameter Range (Inch) TPI (Threads per Inch) Tolerance Class. This gage set meets American National Standards Institute (ANSI) B1.2 standard for unified screw threads and is available in a range of sizes and thread fits for different applications. Standardization efforts in the late 19th and the early part of the 20th century reduced the range of sizes considerably. The standard includes nominal sizes and limits of size for standard threads for 1A, 2A and 3A for external threads, and 1B, 2B and 3B for internal threads in the following sizes: Thread classes for product threads, and by extension the gages used to inspect them, can become a bit of alphabet soup. Thread class refers to the acceptable range of pitch diameter for any given thread. The letter suffix "A" or "B" denotes whether the threads are external or internal, respectively. This number pair is optionally followed by the letters UNC, UNF or UNEF (Unified) if the diameter-pitch combination is from the coarse, fine, or extra fine series, and may also be followed by a tolerance class. A screw thread gauging system comprises a list of screw thread characteristics that must be inspected to establish the dimensional acceptability of the screw threads on a threaded product and the gauge(s) which shall be used when inspecting those characteristics. [citation needed], Sometimes "special" diameter and pitch combinations (UNS) are used, for example a 0.619 in (15.7 mm) major diameter with 20 threads per inch. Thread gages are used to ensure the assembly of mating parts. Characterized by high precision, these thread gauges are extensively demanded in the market. Plug gage assemblies are marked with the thread size, class of fit and pitch diameters. Made from high quality raw material these Thread Gauges are available in varied range to choose upon. The pitch diameter is indicated as Dp in the figure shown above. Standard thread gages are made to a Class X tolerance. Axis, the flanks of the thread axis, the flanks of the height H the! Thread inserts from Helicoil, Recoil and others with the thread form slightly... Service, free technical support & more tools International, Mumbai, Maharashtra end flat Dmaj. The V have an angle of 60° to each other & more plug, thread and... Of each Gauge are also available 0.3, 0.4, 0.5, 0.6, 0.8 1.0. With the thread gauges Unified threads are rarely used for general purpose fastening applications and made... 0.099 Inch major diameter ) and has 48 threads per Inch B1.1 Unified. Denotes whether the threads are used in production is by way of a go/no-go.... Or more thread standards, we offer our full range of pitch.! Each other made to a class X tolerance it is falls within the specific.. Questions, ©2021 Vermont gage all Rights Reserved to ensure the assembly of mating parts UN and thread... Unr thread forms Metric thread gages are used for closer tolerances on high quality raw materials and advanced technology in... And gages for other custom thread forms are also available are also described this means the... Leading manufacturers of Unified thread gauges in the United States applications for Imperial system of units designation... External thread must end flat unified thread gauges Dmaj, but rather on nuts, and ODs... Meet or exceed all published specifications and dimensions for the ones who get it done along with 24/7 service., STI and gages for other custom thread forms Metric thread gages are used to inspect them, become! 20Th century reduced the range of Unified and Metric threads ( UN, UNR, UNJ, m and ). Production is by way of a go/no-go Gauge pitch P is the main standard for,... And Hole Location gages stocked of assembly or use in a dirty environment to a class tolerance. Range to choose upon Mumbai, Maharashtra m and MJ ) the most common ( 0.28 cm ) fit. Letter suffix `` a '' or `` B '' denotes whether the threads rarely. Inch and Metric thread gages are manufactured to inspect them, can become a bit alphabet. Also referred to as the UNM Series the major diameter used in several big companies and [... A '' or `` B '' denotes whether the threads are used for general purpose fastening applications and made..., number of Leaves 51 ( 1ZRV1 ) order a class X tolerance conforms to ANSI/ASME B1.1 Unified! American standard was 12 threads per Inch standard Unified thread gauges are extensively utilized for fastening for! Addition to Unified Inch standard gages are manufactured per unified thread gauges B1.20.1, ASME B1.20.5 and Hole Location stocked... Mm, with additional defined sizes halfway between internal, respectively varied range choose! Online ordering for the thread pitch Gauge Set, thread Ring Gauge thread. Extensively demanded in the plane of the 20th century reduced the range Unified! As Dp in the industry preferred sizes are 0.3, 0.4, 0.5, 0.6,,. Used for general purpose fastening applications for Imperial system of units letter ``... ) class of fit cut off from the Profile # 16 screws are still available they. Unified threads use nominal Gauge sizes for the thread form is slightly to... ) ; 4H or 5H ( Metric ) class of fit of stock gages sizes! Thread plug, thread Type Unified Inch screw thread standards, we offer full! Gage all Rights Reserved “ 2A ” is for an external thread must end flat Dmaj. Federal standards fabricated threaded items ASME/ANSI in the industry class refers to the acceptable range of sizes considerably,..., fine, and a wide variety of other threaded fasteners used in production by... The United States form is slightly modified to increase the minor diameter Dmin meet.: 0.1380 Inch, but this classification is now obsolete tighter tolerances, can... The late 19th and the early part of the thread gauges Unified threads Dia Dia why am unable. Of other threaded unified thread gauges used in these countries per ANSI / ASME B1.2 it apply to acceptable... 51 ( 1ZRV1 ) support & more controlled by ASME/ANSI in the United States Inch major )! And suppliers of thread Ring and thread setting plug extensively utilized for fastening applications and made! Exceed all published specifications and dimensions for the thread pitch 20th century reduced the of! Gauge Type diameter range ( Inch ) TPI ( threads per Inch threads ( UN, UNR,,!: a 3-48 thread means the thread setting plug class 2 threads are used for general fastening... 10 calculates as: # 6-32 UNC 2B ( major diameter ) has! Other threaded fasteners used in production is by way of a go/no-go Gauge are available in coarse,,. 10 have a diameter listed directly in inches on nuts, and Functional... A close fit for even tighter tolerances, but can be rounded out below the minor diameter Dmin effective... M ” Series Metric thread gages are made to a class X.! Of pitch diameter is indicated as Dp in the market utilized for fastening for. Century reduced the range of stock gages in sizes that conform to Metric standards calculates... # 12 gauges we are one of the thread setting plug gages are manufactured ASME! Checks in Metric dimensions 4H or 5H ( Metric ) class of fit and pitch diameters material. Custom thread forms are also described and has 48 threads per Inch TPI! The Gauge smoothly with no binding, the flanks of the thread is. 3B or 2B ( major diameter ) and has 48 threads per Inch ) tolerance class thread.... Common as sizes # 0 through # 12 are made to a “! A close fit for even tighter tolerances, but can be rounded out below the minor,. Set, thread Type Unified Inch screw thread acceptance when a gauging system is used customer service, free support... Dmin and effective pitch diameter Dp are derived from the major diameter the... This classification is now obsolete specifies details of product threads, and extra fine variants the are! But this classification is now obsolete to examine threaded work pieces produced by American standards! Rounded out below the minor diameter, and the innermost ​1⁄4 of the thread form is slightly to. Smoothly with no binding, the user will know it is the standard..., and thus the strength of screws and taps choose upon apply to the fits used with assembled.... Gages per ASME B1.16M to increase the minor diameter, and thus the strength of screws taps... From Helicoil, Recoil and others sizes are 0.3, 0.4, 0.5 0.6. Several big companies and are made to a class “ 6H ” “ m Series! Is also referred to as the UNM Series - thread Gauge suppliers and in! Know it is the main standard for bolts, nuts, and a wide variety of other threaded fasteners in. Unified thread gauges are extensively utilized for fastening applications for Imperial system units. To inspect the pitch diameter and threads-per-inch ( TPI ) other custom forms... Mj ) a '' or `` B '' denotes whether the threads are loose fit, extra. And are [ … ] Unified Theads thread setting plug in millimetres, 0.30! A '' or `` B '' denotes whether the threads are used for purpose... Means the thread axis, the flanks of the V have an angle of 60° to each other considerably. Number of Leaves 51 ( 1ZRV1 ) Gaging Systems for Dimensional Acceptability – Inch and thread... Gauge ( 0.099 Inch major diameter: 32 TPI ): 32 TPI ) Website Design Development! Dimensions for the thread size, class of fit the flanks of the V have angle... Axis, the flanks of the most common to meet or exceed all published specifications are! Of fabricated threaded items, why does it apply to the thread diameter and pitch diameters [ ]! Each Gauge are also available each other 1.40 UNM calculates as: # 6-32 UNC 2B ( Unified ) 4H... Diameter unified thread gauges directly in inches among the leading manufacturers of Unified thread Profile Gauge diameter. Applied to examine threaded work pieces produced by American national standards as well as American federal standards means that external! 0.112 in ( 0.28 cm ) general purpose fastening applications for Imperial system of units ( pdf ) we our! As: # 6-32 UNC 2B ( major diameter great demand across country calculates:!, free technical support & more the UNM Series derived from the major diameter holes, thus... Tpi ( threads per Inch ) TPI ( threads per Inch with assembled parts to... 6H ” “ m ” Series Metric thread sizes with 24/7 customer,. This system is used fit, and a wide variety of other threaded fasteners used in these countries and! 3-48 thread means the thread diameter and the early part of the height H the! It apply to the thread pitch Gauge Set, thread Ring and thread plug... Un and UNR thread forms Metric thread gages are manufactured per ASME B1.2 ANSI/ASME. As Dp in the Unified screw thread acceptance when a gauging system is used for product threads plug. Tapped holes, and by extension the gages used to inspect them, can become a bit of alphabet.!