A691 1/2CR CLASS33 TUBE
A691 1/2CR Class33 Alloy Welded Steel Pipe
A691 1/2CR CL33 welded pipe

A691 1/2CR Class33 EFW Pipe

A691 1/2CR CL33 alloy pipe is a chromium-molybdenum alloy welded pipe of American standard, which adopts electric fusion welding process and is widely used in high temperature and high pressure working conditions.

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Product Introduction

A691 is a standard established by the American Society for Testing and Materials (ASTM). A691 1/2CR Class33 welded pipe is a welded pipe of specific specifications and grades produced in accordance with ASTM A691 standard. It contains 1/2% chromium and 1/2% molybdenum, has the characteristics of high temperature and high pressure resistance, and is used in heat exchangers, nuclear power equipment, chemical pipelines, etc.

A691 Standard specification

1. This specification covers carbon and alloy steel pipe, electric-fusion-welded with filler metal added, fabricated from pressure-vessel-quality plate of several analyses and strength levels and suitable for high-pressure service at high temperatures. Heat treatment may or may not be required to attain the desired mechanical properties or to comply with applicable code requirements. Supplementary requirements are provided for use when additional testing or examination is desired.
2. The specification nominally covers pipe 16 in. [400 mm] in outside diameter and larger with wallthicknesses up to 3 in.[75 mm] inclusive. Pipe having other dimensions may be furnished provided it complies with all other requirements of this specification.

TABLE 1 Plate Materials
Pipe Grade	Type of Steel	ASTM Specification		HB, max A
		Number	Grade
1 ⁄ 2 CR	1 ⁄ 2 % chromium, 1 ⁄ 2 % molybdenum steel	A387/A387M	2	201

TABLE 2 Heat Treatment Parameters A
Pipe Grade	ASTM Specification	Post-Weld Heat-Treat Temperature Range (StressRelieving), °F (°C)	Normalizing Temperature, max unless otherwise noted, °F (°C)	Quenching Temperature, max unless otherwise noted,°F (°C)	Tempering Temperature, min, °F(°C)
1 ⁄ 2 CR	A387/A387M	1100 to 1300 [590 to 705]	1850 [1010]	1700 [925]	1150 to 1375 [620 to 745]

Class designations are as follows
Class	Heat Treatment on Pipe	Radiography, see Section	Pressure Test, see Section
10	none	none	none
11	none	9	none
12	none	9	8.3
13	none	none	8.3
20	stress relieved, see 5.3.1	none	none
21	stress relieved, see 5.3.1	9	none
22	stress relieved, see 5.3.1	9	8.3
23	stress relieved, see 5.3.1	none	8.3
30	normalized, see 5.3.2	none	none
31	normalized, see 5.3.2	9	none
32	normalized, see 5.3.2	9	8.3
33	normalized, see 5.3.2	none	8.3
40	normalized and tempered, see 5.3.3	none	none
41	normalized and tempered, see 5.3.3	9	none
42	normalized and tempered, see 5.3.3	9	8.3
43	normalized and tempered, see 5.3.3	none	8.3
50	quenched and tempered, see 5.3.4	none	none
51	quenched and tempered, see 5.3.4	9	none
52	quenched and tempered, see 5.3.4	9	8.3
53	quenched and tempered, see 5.3.4	none	8.3