Standards Specifications. HeliCoil inserts and tooling comply with the following industry standards and specifications NASM122076 through NASM122275. Patent US5. 09. 26. Buttress thread form. FIELD OF THE INVENTIONThe field of this invention relates to the field of pipe joints. BACKGROUND OF THE INVENTIONThe threads used in connecting basing and tubing pipes together in the oil and gas industry is the single most important part of the overall connector design. These threads are required to resist mechanical loads that often can reach over one million pounds but will not seize or gall after repeated make ups. They determine the overall characteristics of the connector since a problem in the threads can weaken even the best designed seals and torque shoulders. Over the last five decades, major advancements have been developed in thread design beyond the original V shaped thread forms. The most successful threads used in the oil and gas industry have been the tapered V shaped threads, and these threads were expected to perform all the duties of the connector, including pressure sealing while maintaining mechanical strength. As the industry attempted to drill and complete wells with deeper and deeper depths and higher pressures, the simple V shaped thread began to show its limits. One of the most popular designs introduced after the V shaped was the straight, noninterference thread form, which is still very popular today in tubing connectors. This approach removed the sealing duties from the threads by incorporating metal to metal interference fit seals and torque shoulders. By specializing the different parts of the connector for different functions, the connector became a little more predictable. The straight thread has remained popular because of its smooth running characteristics in the field. The next generation of threads designed into connectors for high performance pressure sealing and strength was the tapered, buttress type thread form. These threads have always used radial interference to generate torque that helps resist downhole back off, which has been one of the weaknesses of the straight thread design. Like the straight threads, these tapered thread bodies were used in connectors that incorporated specialized seals and shoulders. But even though these two major design categories were successful over numerous decades of use, they each had limits as to their performance capabilities. The straight thread form, with no radial interference, experienced from time to time downhole back offs caused by heat cycling and rotating the string of pipe. And, while the tapered interference fit thread did not suffer this weakness, it often generated too much circumferential stress in the box, especially during make up and from applied internal pressure. Both of these thread forms suffered a weakness that has become a major problem as well pressures continue to rise and the depths continue to go deeper. The problem is that the threads provided no way for the pin and box to lock together radially, which would allow resistance to pressure inside the pipe that somehow could migrate up into the space between the pin and box. These older thread designs also had the tendency to jump out under very high tension or bending loads because the amount of metal available on the end of a piece of pipe, even with forged ends or coupling, is never adequate for the incorporation of big, tough thread teeth that could resist such loads. It is an impossible task to accurately predict the loads these connectors go through 3 5 miles under the surface of the Earth. These weaknesses have brought on numerous products over the last ten years or so that incorporate a hooked or locking type thread form. These threads utilize at least one of the load flanks being reverse angled or hooked such that when tension loads are applied, the connectors basically draw together or get tighter. This has been a solid breakthrough for the industry, but these designs all have some weaknesses, mostly with resisting compressive or bending loads. Others that do not have this drawback are so sophisticated that the cost of production is very high. The weakness in compression or bending with the current products on the market is created by the clearance these forms require on the compression flank of the thread tooth. The hooked tension flanks work great, but when bending compression on one side and tension on the opposite side or compression is applied in any great quantities, the thread body has no way of carrying those loads because there is no contact on that side of the thread tooth. This usually means that the torque shoulders have to carry these loads and the shoulders are sometimes pressure seals or are adjacent pressure seals. Axial strain generated from this applied compression can be very detrimental to these seals and shoulders. HHI-531762/HHI-531762_4_img-750x750.jpg' alt='Screw Thread Size Tool' title='Screw Thread Size Tool' />This invention includes a thread form design that offers the locking effect so important in todays oil and gas industry but also provides the compressive and bending strength absent in most designs. This means a thread form design that is truly rigid as it can resist extremely high tension loads without experiencing jumpout, is equally capable of carrying the applied compressive and bending loads, and is adequately capable of locking the box and pin together should high gas pressures migrate up into the interstitial space between the pin and box. This invention provides the smooth running and low stress characteristics of the straight or noninterference fit thread form. This invention is cost effective. SUMMARY OF THE INVENTIONThe overall description of this invention is a truncated buttress type thread form that incorporates a reverse angle tension load flank with a compression flank and a torque shoulder the thread does not have any radial interference designed into it, but the hooked tension flank does tend to pull the pin and box together once the torque shoulder is engaged. The mating compression flanks have designed into them a minimum amount of clearance prior to the shouldering action, which then closes to zero or very near zero at the moment the shoulder is engaged. This drawing together is due to the tendency of the hooked threads to pull together at shouldering if there exists no radial interference in the thread body. The thread roots and crests can be tapered, parallel to the taper of the thread body, or flat and parallel to the pipe axis but maintain adequate clearance to allow some closure once the shoulder is engaged so that the compression flanks can draw together. BRIEF DESCRIPTION OF THE DRAWINGSFIG. FIG. 2 shows the configuration during assembly. FIG. 3 shows the configuration as the torque shoulders touch. FIG. 4 shows the final configuration of the hooked threads. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTFIG. FIG. 2 shows the general configuration of the thread form. The pin thread 4 is comprised of a crest 1. The load flank 8 makes an angle A to a line drawn perpendicular to the axis 3 of the thread such that the crest 1. Screw Thread Size Tool' title='Screw Thread Size Tool' />The stab flank 6 forms an angle B to a line drawn perpendicular to the axis 3 of the thread. The angle B is chosen so that the included angle C formed by the load flank 8 and the stab flank 6 is greater than zero degrees. The box thread is designed such that the angles of the load flank 9 and the stab flank 7 are the same as those of the pin. Furthermore, the length l. The thread height l. Screw Thread Size Tool' title='Screw Thread Size Tool' />The preferred angle A is 1. How to Unscrew a Screw Without a Screwdriver. It happens often enough that you dont have a screwdriver handy but really urgently need to remove a screw. Although. 17 NPTF Class 2 Specifications Nominal Size T. P. I. Basic Dimensions for Crest Check Plug Gages Basic Dimensions for Root Check Plug Gages Max. Dia At L3. Types. Screw thread insert types genereally consist of tanged or tangless, freerunning or screwlocking, and both inch and metric sizes. HeliCoil also manufactures. Helicoil,helicoil insert,helicoil inserts,helicoil,helicoil thread repair kit, helicoil tool, helicoil tools,helicoil tool kit, helicoil manufacturer,helicoil. Glossary of Terminology Related to Nuts and Bolts. Presented below is a glossary of terminology on topics related. If you have any questions about any of the content or you. Email. on the topic. Screw Thread Size Tool' title='Screw Thread Size Tool' />A B. C D. E F. G H. I J. K L. M N. O P. Q R. S T. U V. W X. Y Z. We have a web site dedicated to training, have a look at www. ACORN NUT A nut so called because of its shape that has a domed. AEROTIGHT NUT A torque prevailing nut of all metal construction. The. nut is slotted in two places which, after the nut has been. When the. nut is screwed onto the bolt thread the two slotted parts. Their stiffness. causes the nut threads to bind onto the bolt threads and. Aerotight is a registered. The Premier Screw and Repitition Co. Ltd of. Woodgate, Leicester, United Kingdom, LE3 5. GJ. ANTI FRICTION COATING AF coatings are dry lubricants consisting of suspensions. PTFE or molydbenum. Such coatings. can be applied to fastener threads to replace metallic coatings. By careful selection of the lubricants, AF. The coatings are permanently bonded to the metal surface. ANTI SEIZE COMPOUND An anti seize compound is used on the threads of fasteners. The purpose of the compound depends. It can prevent galling of mating surfaces. In some. applications it is used to improve corrosion resistance. Thirdly. it can provide a barrier to water penetration since the. Nokia Mobile Vpn Client Policy Tool on this page. AUTOLOK NUT A torque prevailing nut of an all metal construction. Covered by UK patent 1. GKN. Screws and Fasteners Limited. ALLOWANCE An intentional clearance between internal or external. Not all classes. of fit have an allowance. For metric threads the allowance. ANAEROBIC ADHESIVE An adhesive which hardens in the absence of air, such. A tightening procedure in which a fastener is first tightened. Frequently bolts are tightened beyond their. Bolts of short length can be elongated. Because. of the bolt being tightened beyond yield, its re use is. BASIC THREAD PROFILE This is the theoretical profile of external and internal. BEARING STRESS The surface pressure acting on a joint face directly as. BIHEXAGON HEAD A bolt or screw whose cross section of its head is in. BLACK BOLTS AND NUTS The word black refers to the comparatively wider tolerances. BOLT A bolt is the term used for a threaded fastener, with. BREAKAWAY TORQUE The torque necessary to put into reverse rotation a bolt. BREAKLOOSE TORQUE The torque required to effect reverse rotation when a. BRITISH STANDARD BRASS A specialist thread form based upon the Whitworth thread. BSF British Standard Fine. A thread form based upon the British. Standard Whitworth form but with a finer thread more threads. This thread form was first. BS 8. 4. 1. 95. 6. BSW British Standard Whitworth. A thread form developed by. Sir Joseph Whitworth in 1. The thread form has rounded. BS 8. 4. 1. 95. 6. This thread form was superceded by the Unified thread. BUMP THREAD A modified thread profile patented and trade mark of the. Bosco Tool Inc. The thread form has a small projection at. By doing this it is claimed. CADMIUM ELECTROPLATING Coating of threaded fasteners with cadmium can provide. The appearance. of the coating is bright silver or yellow if subsequently. The friction values associated with this coating. A chromate conversion coating. Cadmium is not now frequently used because of. C or when contact with food is possible. CLAMPING FORCE The compressive force which a fastener exerts on the joint. CLASS OF FIT The Class of Fit is a measure of the degree of fit between. Three main Classes. Fit are defined for metric screw threads FINE This has a tolerance class of 5. H for internal threads. MEDIUM This has a tolerance class of 6. H for internal. threads and 6g for external threads. COARSE This has a tolerance class of 7. H for internal. threads and 8g for external threads. For Unified threads, a similar designation as for metric. The thread classes used are 1. A, 2. A and. 3. A for external threads and 1. B, 2. B and 3. B for internal threads. CLEVELOC NUT A torque prevailing nut of all metal construction. The. collar of the nut is elliptical in cross section and it. The. nut is pre lubricated to reduce the torque needed when tightening. COEFFICIENT OF FRICTION A dimensionless number representing the ratio of the friction. Typically for threaded connections. In relation to threaded fasteners, the coefficent of friction can be further sub divided into the coefficient of friction between the threads and the coefficient of friction under the nut face. There is in general a difference in values between the two coefficients due to typically the contact surfaces being different. For example, a zinc plated nut on a zinc plated bolt, the thread coefficent of friction would be due to zinc plating contacting zinc plating. The nut face coefficient of friction would be due to zinc plating contacting the joint surface finish. COMMINGLING A term used to describe the undesirable practice of mixing. CONELOC NUT The Coneloc is an all metal prevailing torque type self locking nut. The. locking action is achieved by localised precision deformation of the thread. When the nut is tightened onto the. Coneloc is a trade mark of NUTS BOLTS Limited. CONE PROOF LOAD This is an axial applied force applied to a nut when it. Failure in this test is usually due. The intention of the test is to introduce. This type. of test is sometimes applied to nuts which are intended. CREEPCreep is deformation with time when a part is subjected. Metals creep can occur at elevated temperature. Creep resistance is an important property. Gasket materials are designed to flow. The amount of creep sustained tends to increase with temperature. However once the tightening is completed it is important. If this stress is reduced to. DECOMPRESSION POINT The point at which there is zero pressure at the joint. If. the applied force is increased beyond the decompression. Analytically, a. criteria of joint failure is often taken as when the applied. This. is because forces acting on the bolts can dramatically. Loading beyond this point can also. This process can continue until bolt failure does. The failure can be by fatigue or other mechanism. It is for this reason that it is. DACROMET A high performance surface coating that can be applied. The coating consists of passivated zinc flakes. The coating can. be coloured and eliminates the risk of hydrogen embrittlement. DACROMET is a registered. Metal Coatings International, Inc. Chardon. Ohio DESIGN FORM OF THREAD The design form of an internal or external thread is the. It is the same. as the basic thread profile except that the thread roots. If either the internal or external thread form. DIRECT TENSION INDICATORS Direct Tension Indicators DTIs is a term sometimes. Projections on. the face of the washer usually on the face abuting the. An indication of the tension in the bolt can. The smaller the gap the greater. Commonly used in civil rather than. DYNAMIC FRICTION Resistance to relative movement of two bodies that are. EFFECTIVE DIAMETER This is the diameter of an imaginary cylinder coaxial. It is often referred to as pitch diameter. Sometimes referred. EFFECTIVE NUT DIAMETER Twice the effective nut radius. EFFECTIVE NUT RADIUS The radius from the centre of the nut to the point where. ELECTROLESS NICKEL A relatively thin, hard coating that can be applied to. Bright metallic in appearance. EMBEDMENT Localized plastic deformation which occurs in the vicinity. Embedding. is local plastic deformations that occur under the nut face. This occurs even when.