Name of Legally Binding Document: JIS B Taper pipe threads. Name of Standards Organization: Japan Standards Association (JSA). UDC JIS. Japanese Industrial Standard. Designation of thread . r = P. P = n. JIS B ISO (BS21). C JIS B – Download as PDF File .pdf), Text File .txt) or read online. JIS B .

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Even experienced workers sometimes have difficulty jiz threads, regardless of their thread identification procedure and the quality of their gauges. Determine if the thread is tapered or straight parallel. To identify the end connection, you: On the appropriate thread identification reference table, locate the nominal thread diameter.

The male end has a straight thread and an angled shoulder. We will use the following definitions in this manual: Use a caliper to measure the nominal male or female thread diameter from crest-to-crest. At this point you know that the thread has the following characteristics: The female end has a straight thread and a taper to accept the O-ring.

The seal is designed to take place on the tapered thread. The male end has a straight thread and a straight shoulder. The male end has an undersized NPT thread and an O-ring groove on the shoulder of the hex. To determine the thread pitch, use the Swagelok pitch gauges and check the thread against each form until you find a match.

Since the thread is straight, turn to the Straight Thread Identification Reference Table on page 14, and locate the thread diameter. The flanks compress against one another due to the thread taper as the fittings are attached. Pitch Gauge A pitch gauge is used to identify the thread pitch.


Pipe Gauge for Precision Inspection of Tapered Male Pipe Thread (JIS B0203)

The seal takes place by compressing a gasket between the male and female fittings. Because the threads of the mating fittings are parallel to each other, there is no interference between the flanks, crests, and roots.

Measuring the Thread Diameters straight parallel. Though ISO and NPT threads can look similar, they can never be used together, as they have different taper angles, root and crest, b0230 per inch, and pitch, which would result in non-sealing fittings. Consequently, the seal must be made with a gasket, O-ring, or some metal-to-metal contact.

Maryland Metrics: Common types of pipe threads used in the piping industry

Thread Flank Angle 2. Determine the thread standard. Note that a pitch gauge may be Unified threads per inchWhitworth kis per inchor metric millimeters per thread as marked on the back of each gauge form.

Straight or parallel threads are best used as fastening connections since they do not have a leak tight seal. You find that the thread is straight. Tapered threads tighten to create a higher pressure fluid type seal.

The globe seal nose may contain an O-ring. Identify the type of seal.

JIS B 0203: Taper pipe threads

S Measure any full thread. Function, material compatibility, adequate ratings, proper installation, operation, and maintenance b02033 the responsibilities of the system designer and user. See Unified Screw Threads. Determine if the thread is T tapered or S straight parallel. Each end connection, however, will generally have threads that are one of the three most common: Pitch For the purposes of this guide, pitch refers to threads per inch, instead of the distance between the threads, for fractional screw threads and pipe threads.


The male fitting has a straight thread and a spigot which fits through the ID of the gasket. Use a caliper to measure the nominal male or female thread crest-to-crest diameter on the first, fourth, and last full threads. For each case, read across the table to the pitch column to determine the possible thread pitches for your thread.

Calibration of calipers is the responsibility of the end user. The counterbore is larger to help ensure the male end compresses the gasket into a sealing position. Skip to main content. Thread standards are usually referenced in the end connection standard. Locate the end connections that have the tapered thread you identified. The main reason for this variation is industry or manufacturing tolerances.

Therefore, thread standards can be used to help define end connection standards. Nominal thread diameter of 0. It is intended to be used as a guide to help identify various threads. Depending on the application and materials, thread lubricant may be used. If you prefer to narrow down the choices, use the following procedure: T If the diameters increase for a male end or decrease for a female end, the thread is tapered.

The leak tight seal is the reason most process instrumentation use tapered thread connections.

The information in this chart is not intended to be used as inspection criteria for threaded fittings. The complete catalog contents must be reviewed to ensure that the system designer and user make a safe product selection.