Methods of indicating pipe size

Currently, most pressure pipelines and their components have been serialized, supported by corresponding application standards. Therefore, the first consideration in the material design of pressure pipelines is the selection of standard series for the pressure pipelines and their components. Apply the standard system. A collection of series standards used for the various components in a piping system (route). These standards should include standards for pipe series, standards for fitting series, standards for flanges and their connections, valve standards, etc. These standards are applied within a piping system according to certain rules; they are interconnected and work together to determine the basic parameters of the pipes and their components. Among these standards, pipe standards and flange standards are the most representative, as they serve as the basis for other application standards. Currently, there are many standard systems in use around the world. Different industries have their own application standards and standard systems, and these vary considerably from one another; as a result, they cannot be used together or interchanged, which causes quite a bit of trouble for users. Therefore, the first step in pressure pipeline design is to select an applicable standard system, which serves as a unified guideline for the design, so as to prevent errors caused by various related fields adopting incompatible standard systems. Standards applied around the world can be broadly divided into two categories. Pipes – that is, the series of outer diameters for steel pipes are divided into internationally standard series (large outer diameter series) and imperial pipes ； Flanges – European-style flanges and American-style flanges. Methods of indicating steel pipe wall thickness: There are three ways to indicate the wall thickness of steel pipes: the pipe designation, the wall thickness dimension, and the pipe weight. 1) The wall thickness is indicated using the pipe designation “Sch”. 2) It is expressed in terms of the wall thickness of the steel pipe. Some steel pipe standards in China, ISO, and Japan use this method. 3) The wall thickness is indicated by the weight of the pipe; it classifies pipe walls into three categories: a. Pipes with standard weight, denoted as STD; b. Thick-walled pipes, denoted as XS; c. Extra-thick-walled pipes, denoted as XXS. For pipes with DN≤250mn, Sch40 is equivalent to STD, DN

Common standards in the American National Standards Institute’s system of applied standards include: ANSI/ASME B36.10 – Seamless and welded steel pipes; ANSI/ASME B36.19 – Stainless steel seamless and welded pipes; ANSI/ASME B16.9 – Steel butt-welded pipe fittings manufactured in factories; ANSI/ASME B16.11 – Socket-welded and threaded forged pipe fittings; ANSI/ASME B16.28 – Steel butt-welded elbows and tees with small radii; ASME/ANSI B16.34 – Valves with flange, threaded, and welded connections; ASME/ANSI B16.5 – Pipe flanges and flanged pipe fittings; ASME/ANSI B16.36 – Orifice plate flanges; ASME/ANSI B16.42 – Ductile iron flanges and flanged pipe fittings; ASME/ANSI B16.47 – Large-diameter steel flanges; ASME/ANSI B16.20 – Spiral, wrapped gaskets, and metal gaskets for pipe flanges; ASME/ANSI B16.21 – Non-metallic flat gaskets for pipe flanges; ASME/ANSI B18.2.1 – Square and hex head bolts and threads; ASME/ANSI B18.2.2 – Square and hex head nuts; API Std 605 – Large-diameter flanges and flange covers; API Std 526 – Steel pressure relief valves with flange connections; API Std 598 – Inspection and testing of valves; API Std 599 – Metal plug valves with flange and welded connections; API Std 600 – Steel gate valves with flange and butt-welded connections; API Std 602 – Small steel gate valves (compact gate valves); API Std 603 – Flanged valves for 150-pound corrosion resistance applications; API Std 608 – Metal ball valves with flange and butt-welded connections; API Std 609 – Lugged and clamp-type butterfly valves; API Std 6D – Specifications for pipeline valves; MSS SP-44 – Necked slip-on flanges

Common standards in Japan’s application standard system JIS include: JIS G3452 Carbon steel pipes for general use; JIS G3454 Carbon steel pipes for pressure applications; JIS G3455 Carbon steel pipes for pressure applications; JIS G3456 Carbon steel pipes for high-temperature use; JIS G3457 Carbon steel pipes for arc welding; JIS G3458 Alloy steel pipes; JIS G3459 Stainless steel pipes; JIS G3468 Large-diameter stainless steel pipes for arc welding; JIS B2201 Pressure classes for ferritic material pipe flanges; JIS B2202 Dimensions of pipe flanges; JIS B2210 Basic dimensions of ferritic material pipe flanges; JIS B2220 Steel pipe flanges; JIS B2302 Steel threaded connection fittings; JIS B2311 Steel butt-welded fittings for general use; JIS B2312 Steel butt-welded fittings; JIS B2313 Butt-welded fittings made of steel plates; JIS B2316 Socket weld fittings; JIS B2401 O-rings; JIS B2404 Spiral wound gaskets for pipe valves; JIS B3453 Compressed asbestos gaskets

Common standards used in the ISO application standard system include: ISO6708 – Definitions of nominal sizes for pipe fittings; ISO7268 – Definitions of nominal pressures for pipe fittings; ISO4200 – Dimensions and weight per unit length for welded and seamless straight-end steel pipes; ISO1127 – Dimensional tolerances and weight per unit length for stainless steel pipes; ISO3183 – Steel pipes for use in the oil and gas industry; ISO6759 – Seamless steel pipes for use in heat exchangers; ISO7005-1 – Metal pipe flanges; ISO7483 – Gaskets for pipe flanges that comply with ISO7005 standards; ISO3419 – Pipe fittings made of non-alloy and alloy steels; ISO5251 – Butt-welded stainless steel pipe fittings; ISO7121 – Flanged steel ball valves; ISO10497 – Valve testing – Requirements for fire resistance testing

Domestic: Common standards in the application standard system for the petrochemical industry – SH3401: Asbestos rubber gasket for pipe flanges; SH3402: PTFE-coated gasket for pipe flanges; SH3403: Metal ring gasket for pipe flanges; SH3404: Fasteners for pipe flanges; SH3405: Size series for steel pipes in petrochemical enterprises; SH3406: Steel pipe flanges for petrochemical use; SH3407: Winded gasket for pipe flanges; SH3408: Welded seamless steel pipe fittings; SH3409: Welded pipe fittings made of steel plates; SH3410: Socket-welded pipe fittings made of forged steel

Common standards in the application standard system for the chemical industry.. HG20537.1 Specifications for the selection of welded austenitic stainless steel pipes; HG20553 Series of specifications for the selection of seamless and welded steel pipes for use in chemical piping systems; HG/T21634 Welded fittings made of forged steel; HG/T21635 Butt-welded fittings made of carbon steel and low-alloy steel; HG/T21631 Seamed butt-welded fittings made of steel; HG/T21632 Welded, threaded, and butt-welded pipe ends made of forged steel; HG/T21637 Filters for chemical pipelines; HG/T21577 Quick-special connectors; HG20592~20605 Steel pipe flanges (European system); HG20615~20626 Steel pipe flanges (American system); HG20606~20612 Gaskets for steel pipe flanges (European system); HG20627~20633 Gaskets for steel pipe flanges (American system); HG20613 Fasteners for steel pipe flanges (European system); HG20634 Fasteners for steel pipe flanges (American system)

Common standards in the application standard system of the machinery industry include: JB/T74 – Technical requirements for pipeline flanges; JB/T75 – Types of pipeline flanges; JB/T79.1–79.4 – Flanges for integrally cast steel pipes; JB/T81 – Plate-type butt-welded steel pipe flanges; JB/T82.1–82.4 – Welded steel pipe flanges; JB/T83 – Butt-welded ring-type loose-flange steel pipe flanges with pressures of 0.25, 0.6, 1.0, 1.6, and 2.5 MPa; JB/T84 – Concave-convex face butt-welded ring plate-type loose-flange steel pipe flanges with pressures of 4.0, 6.3, and 10.0 MPa; JB/T85 – Flanged loose-flange steel pipe flanges with flanging, for pressures of 0.25 and 0.6 MPa; JB/T86.1–86.2 – Covers for steel pipe flanges; JB/T4700–4703 – Flanges for pressure vessels; JB/T87–90 – Gaskets for pipeline flanges; JB4704–4706 – Gaskets for pressure vessels