Plug

The screw plug is used at the end of the pipe to prevent leakage of the pipe and play a sealing role. It is a commonly used pipe fitting in the installation of the water heating system, with a nominal pressure of 1-1.6Mpa

General advantages of the plug

1. Chemical resistance: it is not easy to be corroded by sewage and wastewater, nor by soil rotting substances

2. Cold resistance: there is no frost crack and expansion leakage of the pipe in the ultra-low temperature environment of minus 60 ℃

3. It is generally made of plastic or metal iron. No corrosion, scaling, firmness and leakage

Plug specifications are usually distinguished by thread specifications. In inches, one inch equals 8 points, 1/4 inch equals 2 points, and so on

According to different shapes, it can be divided into: outer square, outer hexagon, inner hexagon, etc

According to different materials, it can be divided into carbon steel, stainless steel, copper, plastic, etc

According to different surface treatment, it can be divided into: blackening, zinc plating, nickel plating, chromium plating, etc

At present, the thread specifications commonly used for screw plugs can generally be divided into three categories:

1. Inch pipe threads (55 °)

, including: general sealed pipe threads (R), unsealed pipe threads (G), and old inch pipe threads (PT, PF) in South Korea and Japan

2. American pipe threads (60 °)

include: general sealing pipe threads (NPT, NPSC), dry sealing pipe threads (NPTF, NPSF, NPSI, PTF-SAESHORT), and non sealing pipe threads (NPSM, NPSL, NPTR, NPSH, NH, NHR)

3. Metric pipe threads (60 °)

include: general sealed metric pipe threads (MC, MP) and unsealed metric pipe threads (M)

In the old mechanical drawing standards of China, the code of 55 ° sealed taper pipe thread is ZG, and the code of 60 ° general sealed taper pipe thread is Z

In the new mechanical drawing standards of China, 55 ° sealed taper pipe thread is changed to column internal thread/taper external thread (RP/R1), taper internal thread/taper external thread (RC/R2), and 60 ° general sealed taper pipe thread is coded as NPT (formulated according to American standards)

The new and old 55 ° non sealed cylindrical pipe thread codes are G