All types of steel pipes for water and gas with or without zinc coating, threaded by cutting or by smelting or not threaded, that are made with nominal diameter and wall thickness according to GOST 3262-75. Assortment of pipes must correspond to GOST 3262-75. The pipes are made with lengths:
- standardized lengths - from 4m to 12m;
- proportional to standardized lengths - not more than standardized size, with an allowance for each cut of 5 mm and a longitudinal deviation of the entire length + 10 mm;
- non-standardized lengths, within standardized lengths.
By agreement between manufacturer and consumer in every batch of non-standardized length pipes there may be up to 5% of the pipes with lengths from 1.5 to 4 m. For threading purposes, done by rolling, the pipe inner diameter can be decreased by up to 10% along the thread. The mass of every 1m of pipe is calculated with steel density of 7,85 g/cm3. Zinc coated pipes are heavier than non-zinc coated by 3%. Water and gas steel pipes are separated by precision class:
- normal precision
- increased precision
Normal precision steel pipes for water and gas are made from steel grades listed in GOST 380 and GOST 1050 without the norming of mechanical properties and chemical composition. These pipes are used for water supply, gas supply, and heating systems.
Increased precision water and gas steel pipes are made from steel grades according to GOST 1050 without the norming of mechanical properties or chemical composition. This type of pipes is used for parts of water and gas supply machinery. Steel pipes for water and gas are electrically wielded (with reinforced seams). Depending on the thickness of the pipe wall can be light, ordinary and reinforced. The wall thickness is normalized according to GOST 3262-75.
With the requirement from the consumer ordinary and reinforced pipes with inner diameter of more than 10mm can be threaded from both ends. The thread can be long or short. Pipes can be supplied without thread, without coupling (wo/ t, wo/c), or with a threaded coupling with (w /t, w/ c).
Sometimes the size of the steel water-gas pipes stated in inches. Explanation inches: 8mm - quarter of an inch; half an inch - 15 mm; three-quarters of an inch - 20 mm; inch - 25 mm; inch and a quarter - 32 mm; half an inch - 40 mm; two inches - 50 mm; two and a half inches - 65 mm; 4 inches - 100mm.