Pipe Threads

Fittings. Fittings connect pipes and provide for the attachment of equipment to change flow direction. They must be easily cleaned inside and out, have no exposed pipe threads, and, if of the detachable type, have an appropriate gasket. The fittings are constmcted of the same or similar materials as the pipeline and are installed on tubing. Standard shapes and sizes are specified by the 3A Standards Committee. 

Threaded Joints Pipe with taper-pipe-thread ends (Fig. 10-128), per ANSI B2.1, is available 12 in and smaller, subject to minimum-wall limitations. Fittings and valves with taper-pipe-thread ends are available in most pipe metals. 

Flexible Metal Hose Deeply corrugated thin brass, bronze, Monel, aluminum, and steel tubes are covered with flexible braided-wire jackets to form flexible metal hose. Both tube and braid are brazed or welded to pipe-thread, union, or flanged ends. Failures are often the result of corrosion of the braided-wire jacket or of a poor... 

Drum has 2-in and 14-in national-pipe-thread (NPT) openings in head. 

Tape may be made by a similar process. In this case the lubricant selected is a non-volatile oil. The preform is placed in the extruder and a rod extruded. The rod is then passed between a pair of calender rolls at about 60-80°C. The unsintered tape is often used for lapping wire and for making lapped tube. Sintering is carried out after fabrication. The current most important application of unsintered tape is in pipe-thread sealing. 

ANSI-B 1.20.1 Pipe Threads, General Purpose ANSI-B46.1 Surface Texture ANSI-BI6.5 (1988) Pipe Flanges and Flanged Fittings ANSI-B3 1.3 (1990) Chemical Plant and Petroleum Piping... 

Use of threaded connections shall be minimized and in no case shall be larger than 1-1/2 inches. Pipe threads shall conform to ANSI 61.20.1. 

Supporting the hydrated ferric oxide chips is a combination of a perforated, heavy metal support plate and a coarse support packing material. This material may consist of scrap pipe thread protectors and 2-3-in. sections of small diameter pipe. This provides support for the bed, while offering some protection against detrimental pressure surges. 

Rotary hose external connections (i.e., the connection to the swivel gooseneck) are threaded with line-pipe thread as specified in API Specification 5B [14]. 

Lead. For pipe thread inspection purposes, lead is defined as the distance from a point on a thread to a corresponding point on the adjacent thread measured parallel to the thread axis (Figure 4-373). 

API Specification 5B API Specification for Threading, Gaging, and Thread Inspection of Casing, Tubing, and Line Pipe Threads, API, Dallas, March 1979. 

In standard pipe threads, the flanks come in contact... 

Threaded connectors (Figure 40.34) are made with standard pipe threads cut on the inside surface (female). The end of the pipe is threaded with outside threads (male). Standard pipe threads are tapered slightly to ensure tight connections. The amount of taper is approximately inch in diameter per foot of thread. 

Another material used on pipe threads is sealant tape. This tape, which is made of Teflon, provides an effective means of sealing pipe connections and eliminates the necessity of torquing connections to excessively high values in order to prevent leaks. It also provides for ease of maintenance whenever it is necessary to disconnect pipe joints. The tape is applied over the male threads, leaving the first thread exposed. After the tape is pressed firmly against the threads, the joint is connected. 

Galvanised steel pipes Threaded mild-steel tube is the cheapest material for water pipes, but it is not normally used owing to the amount of rust introduced into the water as a result of corrosion. Galvanised mild-steel tube overcomes this problem and may be used for nearly all hard waters, but it is not satisfactory for soft waters or those having a high free-carbon-dioxide content. The ability of a water to form a scale is, therefore, of prime importance when considering the suitability of galvanised steel for an installation. 

New boilers, heat exchangers, and other equipment must be provided with a PCC program to remove oil, grease, mill scale, pipe-threading compounds, drawing compounds, and other detritus that otherwise prevent the formation of clean, passivated metal surfaces and encourage... 

This expression is only approximate, as it does not make any allowance for the effects of such things as pipe threads, corrosion, or wall damage. To compensate for these factors, an additional allowance is made for the wall thickness in the working definition of the schedule thickness, ts ... 

Ferrous Pipe Plugs, Bushings, and Locknuts With Pipe Threads... 

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. 

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