A691 CM70 EFW Electric Fusion Welded Pipe

A691 Cm70 EFW Electric Fusion Welded Pipe
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A691 CM70 EFW Electric Fusion Welded Pipe

A691 CM70 electric fusion welded pipe is a straight seam electric fusion welded pipe that complies with the American standard (ASTM A691). It is mainly used in high pressure and high temperature conditions in the fields of power and chemical industry.

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Product Introduction

A691 CM70 EFW Pipe Description

‌A691 CM70‌ EFW welded pipe is the code for chromium-molybdenum alloy steel pipe under the American Society for Testing and Materials (ASTM) standard, designed for high pressure and high temperature conditions:

‌Material composition‌: Chromium (Cr) content 1.25%-1.5%, molybdenum (Mo) content 0.45%-0.65%, supplemented by carbon, manganese and other elements to enhance heat resistance and corrosion resistance‌.
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Grade identification‌:
‌CM70‌ represents the material grade (CM represents chromium-molybdenum steel, 70 is the strength grade);
‌Suffix (such as CL22)‌ indicates the heat treatment and inspection level (for example, CL22 requires -29℃ low temperature impact toughness)‌.
‌Manufacturing process‌: Adopt ‌Electric fusion welding (EFW)‌ technology, including submerged arc welding (SAW) or high frequency welding (HFW), to ensure full penetration welds on both sides‌.

Key technologies of manufacturing process

Raw material control

Pressure vessel grade steel plates are used, and the sulfur and phosphorus content is strictly limited (S≤0.010%, P≤0.025%).

Forming and welding

Sheet forming: JCOE (progressive bending) or UOE (molding) process, roundness accuracy ±0.5mm;
Welding process: double wire submerged arc welding (SAWL), online heat treatment after welding to eliminate stress.

Post-processing and testing

Heat treatment: normalizing (920℃±10℃) + tempering (680-720℃), holding time is calculated according to wall thickness;
Non-destructive testing: 100% radiographic testing (RT) and ultrasonic testing (UT), water pressure test up to 1.5 times the design pressure.

A691 CM70 EFW Pipe specification

Product Name		A691 CM70 EFW Pipe
OD		≥405mm
Thickness		2mm~75mm
Unit length		3m, 5.8m, 6m, 11.8m, 12m, 13.5m or as per customers' request
Material		1CR, 3CR, 5CR, 9CR, 91, etc.
surface		Bare surface,varnish painting,galvanizing,other painting as per customers' request
Packing		In bundles with steel strip or in loose, non-woven fabrics packings or as per customers' request
Application		Civil engineering, architecture, steel towers, shipyard, scaffoldings, struts, piles for suppression of landslide and other structures