Guide to Commonly Used Pipe Fitting Standards
Date:2025-11-19
I. Why are standards so important?
Pipe fitting standards standardize dimensions, pressure ratings, materials, tolerances, testing methods, and marking methods. This brings:
Interchangeability: Pipe fittings of the same standard from different manufacturers can be used interchangeably, simplifying procurement and maintenance.
Safety: Standards specify strict pressure carrying capacity and material requirements, ensuring safe operation under harsh conditions.
Economy: Standardized production reduces manufacturing costs and improves supply chain efficiency.
Reliability: Unified testing and inspection methods ensure stable product quality.
Globally, two major systems have emerged, represented by American standards (ASME/ANSI) and European standards (DIN/EN). Chinese national standards (GB) also play a core role in the domestic market.
II. Detailed Explanation of Mainstream Pipe Fitting Standard Systems
1. American Standard System - ASME/ANSI
This is the most widely used and influential standard system globally, especially in the oil, chemical, and power industries.
ASME B16.9 - Factory-Made Forged Steel Welded Pipe Fittings
Core Content: Specifies the dimensions, tolerances, and pressure ratings of welded pipe fittings (such as elbows, tees, reducers, and caps) made of carbon steel, alloy steel, and stainless steel.
Scope of Application: Applicable to all pressure piping systems; one of the most common standards used in project procurement.
ASME B16.11 - Socket Welded and Threaded Forged Pipe Fittings
Core Content: Specifies the pressure ratings, dimensions, and tolerances of socket welded and threaded pipe fittings (such as elbows, tees, caps, and unions).
Scope of Application: Commonly used in small-diameter (DN ≤ 100), high-pressure instrumentation lines, utilities, and other applications.
ASME B16.5 - Pipe Flanges and Flange Fittings
Core Content: Covers the pressure ratings, dimensions, sealing surface types, and materials of flanged pipe fittings such as flanges and blind flanges.
Scope of Application: A cornerstone standard for flanged connection systems.
ASTM A234 / A403:
These are not dimensional standards, but material standards. ASTM A234 applies to carbon steel and alloy steel pipe fittings, while ASTM A403 applies to stainless steel pipe fittings. They are used in conjunction with dimensional standards such as ASME B16.9 to define the complete specifications for pipe fittings.
2. European Standards System - DIN / EN: Widely used in Europe and regions heavily influenced by European technology (such as the Middle East and parts of Asia).
DIN 2605 / DIN 2615 / DIN 2616 / DIN 2617:
These are classic standards for butt-welded pipe fittings in the German Industrial Standards (DIN), specifically for elbows, tees, reducers, and caps. Although gradually being replaced by EN standards, they are still used in many older projects and specific fields.
EN 10253 - "Butt-welded pipe fittings"
Core content: This is a unified EU standard, gradually replacing national standards (such as DIN). It is divided into several parts, such as EN 10253-1 (general purpose) and EN 10253-2 (heavy purpose).
Features: It differs from the ASME standard in terms of size and wall thickness series, mainly using outer diameter series (such as DN series) and wall thickness grades (such as Series 1, Series 2).
