According to Section 2.4 of Drawing Standard for Water Supply and Drainage (gb/t50 106-200 1):
1, water gas conveying steel pipes (galvanized and non-galvanized), cast iron pipes and other pipes, and the pipe diameter is marked as dn (mm);
2, seamless steel pipe, welded steel pipe (straight seam or spiral seam), copper pipe, stainless steel pipe and other pipes, pipe diameter marked as external diameter dx wall thickness;
3, reinforced concrete (or concrete) pipes, clay pipes, acid-resistant ceramic pipes and other pipes, pipe diameter marked D;
4, plastic pipe diameter should be marked according to the product standard method; When designing pipe diameter with dn, there should be a comparison table between dn and corresponding product specifications. Generally, the diameter of plastic pipe is expressed by the outer diameter according to the method of product standard, such as upuc pipe labeled as de and HDPE pipe labeled as de.
Extended data:
Classification of steel pipes:
1, according to the production method
Steel pipes can be divided into seamless steel pipes and slotted steel pipes according to production methods, which are referred to as straight welded steel pipes for short. ① Seamless steel tubes can be divided into hot-rolled seamless tubes, cold-drawn tubes, precision steel tubes, hot-expanded tubes, cold-spun tubes and extruded tubes according to production methods. Seamless steel pipe is made of high-quality carbon steel or alloy steel, which is divided into hot rolling and cold rolling (drawing).
② Welded steel pipes are divided into furnace welded pipes, electric welding (resistance welding) pipes and automatic arc welded pipes according to different welding processes, straight welded pipes and spiral welded pipes according to different welding forms, as well as round welded pipes and special-shaped (square, flat, etc.). ) welded pipes because of their end shapes.
Welded steel pipes are made of steel plates by butt welding or spiral welding. According to the manufacturing method, it is divided into welded steel pipes for low-pressure fluid transportation, spiral welded steel pipes, direct rolled welded steel pipes and welded steel pipes. Seamless steel pipes can be used in various industries, such as liquid pneumatic pipelines and gas pipelines. Welded pipes can be used for water pipelines, gas pipelines, heating pipelines, electrical pipelines, etc.
2, according to the material
Steel pipes can be divided into carbon pipes, alloy pipes and stainless steel pipes according to the pipe material (i.e. steel grade). Carbon pipes can be divided into ordinary carbon steel pipes and high-quality carbon structural pipes. Alloy tubes can be divided into low alloy tubes, alloy structural tubes, high alloy tubes and high strength tubes. Bearing tube, heat-resistant and acid-resistant stainless steel tube, precision alloy tube (such as kovar alloy), high temperature alloy tube.
3. Classification by connection mode
Steel pipes can be divided into: smooth pipe (with no thread at the end) and turning pipe (with thread at the end) according to the connection mode of pipe ends. Turning wire tube is divided into: ordinary turning wire tube and end thickening turning wire tube. Thickened steering tubes can be divided into external thickening (with external threads), internal thickening (with internal threads) and internal and external thickening (with internal and external threads). According to thread types, lathe tubes can also be divided into: ordinary cylindrical or conical threads and special threads. In addition, according to the needs of users, automobile wire tubes are generally delivered with pipe joints.
4, according to the coating characteristics
Steel pipe can be divided into black pipe (uncoated) and coated pipe according to the characteristics of surface coating. Coated pipes include galvanized pipes, aluminized pipes, chromium-plated pipes, aluminized pipes and steel pipes with other alloy layers. The coating tube includes an outer coating tube, an inner coating tube and inner and outer coating tubes. Commonly used coatings include plastic, epoxy resin, coal tar epoxy resin and various glass anticorrosive coatings. Galvanized pipes are divided into KBG pipes, JDG pipes and threaded pipes.
5, according to the purpose
① Pipes for pipelines. Such as: seamless pipes for water pipes, gas pipes, steam pipes, oil pipelines and oil and gas trunk lines. Water pipes for agricultural irrigation taps and sprinkler irrigation.
(2) thermal equipment pipeline. Such as boiling water pipes and superheated steam pipes of general boilers, superheated pipes, large smoke pipes, small smoke pipes, arched brick pipes and high-temperature and high-pressure boiler tubes of locomotive boilers.
③ Pipes for mechanical industry. Such as aviation structural tubes (round tubes, elliptical tubes and flat elliptical tubes), automobile semi-axle tubes, axle tubes, automobile tractor structural tubes, oil cooler tubes for tractors, square tubes, rectangular tubes for agricultural machinery, transformers and bearings.
④ Pipes for petroleum geological drilling. Such as: petroleum drill pipes, petroleum drill pipes (square drill pipes and hexagonal drill pipes), drilling tappets, oil pipes, petroleum casings and various pipe joints, geological drill pipes (core pipes, casings, movable drill pipes, drilling tappets, clamping sleeves and pin joints, etc.). ).
⑤ Chemical pipes. Such as: petroleum cracking pipes, heat exchanger pipes, chemical equipment pipes, stainless acid-resistant pipes, high-pressure pipes for chemical fertilizers, pipes for conveying chemical media, etc.
⑥ Other departments use pipelines. Such as: tubes for containers (tubes for high-pressure gas cylinders and general containers), tubes for instruments, tubes for watch cases, injection needles and tubes for medical devices.
6, according to the cross section shape
There are many kinds of steel grades and specifications of steel pipe products, and their performance requirements are also different. All these should be different with the change of user requirements or working conditions. Steel pipe products are generally classified according to section shape, production method, pipe, connection mode, coating characteristics and uses. Steel pipes can be divided into round steel pipes and special-shaped steel pipes according to their cross-sectional shapes.
Special-shaped steel pipe refers to various steel pipes with non-circular cross section. Among them: square tube, rectangular tube, elliptical tube, flat elliptical tube, semicircular tube, hexagonal tube, hexagonal inner tube, equilateral hexagonal tube, equilateral triangular tube, pentagonal pentagonal tube, octagonal tube, convex tube and biconvex tube. Double concave tubes, multiple concave tubes, melon seeds tubes, flat tubes, rhombic tubes, star tubes, parallelogram tubes, ribbed tubes, downcomers, inner finned tubes, twisted tubes, B tubes, D tubes and multilayer tubes.
Steel pipes can be divided into equal cross-section steel pipes and variable cross-section steel pipes according to the longitudinal cross-section shape. Variable cross-section (or variable cross-section) steel pipe refers to the steel pipe whose cross-section shape, inner and outer diameters and wall thickness change periodically or aperiodically along the length of the pipeline. It mainly includes: outer conical tube, inner conical tube, outer stepped tube, inner stepped tube, periodic section tube, corrugated tube, spiral tube, finned steel tube and multi-line cylinder.
References:
Steel pipe? Baidu baike