![]() Spacing the wrenches too far apart applies additional torque to the joint and can damage the pipe or body. Wrenches should be used as close to the joint as possible without damaging the threads. Torque increases more quickly when tightening Schedule 80 steel pipe and cast iron threaded products than Schedule 40 pipes. Excessive tightening may be attempted to stop the leak when this may only cause more damage. Improperly gaging threads and dirty or damaged threads can prevent joints from sealing. Tape lessens the torque and leads to excessive thread engagement In addition, do not back off a fitting after it has been tightened. Overtightening beyond the sealing torque continues to wedge the pipe into the body and can crack the female thread. Pipe threads seal by metal-to-metal interference over the tapered surface area with increasing forces as it tightens. Please keep in the mind the following additional tips and tricks:Īn NPT joint is formed by wedging the male thread into a female thread. ![]() Always verify that the seal is completed by testing the joint. A complete turn beyond this sealing torque will increase torque by about 100 foot-pounds. A sealed assembly is easily attainable while using the smallest available wrenches (12”-18”). Typical sealing occurs by one turn past hand tight at the approximate values on the table to the right. The total thread engagement should be between 3.5 and 6 threads. Keep the above issues from happening in the first place by understanding that the recommended* tightening is hand tight plus 1-1 1/4 turns when using properly gaged threads and appropriate pipe dope. Improper use of wrenches (use a smooth jaw on a hexagon or octagon).Threads do not meet NPT gaging requirements.However, there are a number of problems that can affect the NPT thread seal of 3/4”, 1 1/4”, and 2” NPT threads with Schedule 40 steel pipe, Schedule 80 steel pipe, and cast iron fittings, such as the following: NPT thread is commonly used on the parts that make up and surround a natural gas meter set. As knowledge that every natural gas provider can benefit from knowing, consider this your complete guide to creating a gas tight seal with National Pipe Threads (NPT). One way in which both safety and efficiency can be optimized is by creating a proper gas tight seal at the meter set. When dealing with natural gas, safety is always a top concern. The Gas Expert's Guide to Creating a Gas Tight Seal with NPT Thread
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