Tapered thread

Flanged Bolted flange connectors. Figure 40.35, are suitable for most pressures now in use. The flanges are attached to the piping by welding, brazing, tapered threads... 

Seal Welding. Seal welding taper-threaded joints should be considered for hydrogen gas inside buildings. Taper-threaded joints shall not be seal welded unless the composition of the metals in the joint is known and proper procedures for those metals are followed. Thread sealants shall not be used and the weld material shall cover the full circumferential length of the thread. 

Unless otherwise specified, pipe threads shall be tapered threads conforming to ANSI/ASME Bl.20.1. Tapped openings and bosses for pipe threads shall conform to ANSI/ASME B 16.5. 

Pipe threads shall be taper threads in accordance with ANSI/ASME B 1.20.1. Pipe threads in accordance with ISO 228 Part 1 are an aeeeptable alternative when reqnired for comphanee with loeal standards. Flanges shall be in accordance with ISO 7005 (ANSI/ASME B 16.5). Slip-on flanges are permitted only with the purehaser s speeifie approval. For socket welded construction, a 1.5 mm (0.06 in.) gap shall be left between the pipe end and the bottom of the socket (2.3.3.S). 

Straight Pipe Threads These are confined to light-weight couplings in sizes 2 in and smaller (Fig. 10-132). Manufacturers of threaded pipe ship it with such couplings installed on one end of each pipe. The joint obtained is inferior to that obtained with taper threads. The code limits the joint shown in Fig. 10-129 to 1.0 MPa (150 Ibftin ) gauge maximum, nontoxic fluids. 

Fig. 10.9. Normal pipe threaded joint. Note the tapered threads on both the male and female components. Unlike most other joints, the seal is formed in ihe threaded portion of the joint.

Thermal relief valves specified with threaded ends shall have internal, NPT-type, female-tapered threads. 

Thread start—style of start (abrupt, tapered) Thread helix angle... 

Where pressure-tight joints are required, BSP taper threads have to be used. These have the same form and number of threads, but the thread is tapered at 1 in 16. 

Coarse threads can be molded into most materials. Threads of 32 or finer pitch should be avoided, along with tapered threads, such as pipe threads. These types of threads can cause excessive stress. Other factors that should be considered when designing molded-in threads are ... 

Machine screws and bolts. Parts molded of thermoplastic resin are sometimes assembled with machine screws or with bolts, nuts, and washers (Fig. 9.8), especially if it is a very strong plastic. Machine screws are generally used with threaded inserts, nuts, and clips. They are rarely used in pretapped holes. Molded-in inserts provide very high-strength assemblies and relatively low unit cost. However, molded-in inserts could increase cycle time while the inserts are manually placed in the mold. When the application involves infrequent disassembly, molded-in threads can be used successfidly. Coarse threads can be molded into most materials. Threads of 32 or finer pitch should be avoided, along with tapered threads, because of... 

Two basic types of threads are used in the United States and Canada straight thread and tapered thread. The straight thread requires use of an 0-ring or gasket to accomplish a gas-tight seal. (See Fig. 9-7.) This type of thread requires less installation torque than a tapered thread and is mostly used with aluminum cylinders. Common sizes currently in use are 0.750-16UNF and 1.125-12UNF. Most commonly used are the... 

The 3/4 - 14SGT (Special Gas Taper Thread) is a standard having a taper of 11/2 per foot equivalent to ( 12.50 mm per 100 mm) on diameter with a 60° thread normal to the axis and 0.0618 (1.570 mm) deep. For this thread Col. 13, 14 and 15 are based on gages 0.7030" (17.856 mm) long. Cylinders are held to final inspection limits from basic to 1 1/2 turns small, and valves to plus or minus 1 turn. 

National Gas Tapered (threads) National Institute of Occupational Safety and Health National Institute of Standards and Technology Nonvolatile Residue... 

For further information on cylinder valve inlet connections and other thread types presently in use, that is. Special Gas Taper Threads (SGT) and National Gas Straight Threads (NGS), refer to CGA V-1, American National, Canadian, and Compressed Gas Association Standard for Compressed Gas Cylinder Valve Outlet and Inlet Connections, [1]... 

Valve parts such as valve handwheels and valve stems should not be broken or bent and must be intact. Valves with tapered threads at the cylinder connection should have a portion of threads exposed to ensure... 

A straight or tapered fine thread is provided in the mandrel-holder to secure the mandrel. The tapered thread which permits of changing the mandrel rapidly, has not found a wide application as the mandrel tends to loosen easily. 

It can be used on its own with smaller threaded fittings like those on models and is quite suitable for steam fittings. Where proper tapered threads are not used the joint should be screwed up tight or, if the fitting must be located at a certain angle, a locknut should be fitted to fasten it in the desired position. 

---