What is ASTM A691 1CR Pipe?

ASTM A691 1CR is a chromium-molybdenum alloy grade with 1% chromium and 0.5% molybdenum. This specification covers electric fusion-welded pipe for high-temperature and high-pressure service. The A691 1CR pipe is equivalent to P12 or Grade 12 material. Chromium provides oxidation resistance at elevated temperatures. Molybdenum provides creep strength so the pipe performs well during sustained high-temperature operation. These properties make 1CR suitable for demanding applications in power generation and petrochemical facilities.

Specification of ASTM A691 1CR Pipe

The technical specifications for ASTM A691 Grade 1CR chrome moly pipes as per the ASTM A691 standard are given below:

Standard ASTM A53 / ASME SA53
Types Seamless / ERW / Welded / Fabricated / LSAW Pipes
Grades 1/2 CR, 1 1/4 CR, 2 1/4 CR, 3 CR
Pipes Size 16” to 60”
Thickness SCH 2o, SCH 40, SCH STD, SCH 80
Surface Painted, Natural, 3PE, FBE

Chemical Composition of ASTM A691 Grade 1CR Pipe

The following table outlines the chemical composition requirements for ASTM A691 Grade 1CR chrome-molybdenum pipe:

Specification C % Mn % P % Max S % Max Si % Cr % Mo %
ASTM A691 Gr 1CR 0.05-0.17 0.40-0.65 0.025 0.025 0.15-0.40 0.80-1.15 0.45-0.60

Heat Treatment

The heat treatment requirements for ASTM A691 1CR pipes are as follows:

  • Normalising: 900–930°C (1650–1700°F)
  • Tempering: 620–720°C (1150–1325°F)
  • Post-Weld Heat Treatment: Required per ASME code

Applications of A53 Gr B pipe

The ASTM A691 1CR chrome moly pipe serves high-temperature industrial applications where material reliability matters.

Power Plant Piping

A691 1CR pipes are used for steam lines and high-temperature piping in thermal power plants. The combination of creep strength and oxidation resistance works well at high temperatures. These pipes can handle the tough conditions of power generation where failures can be very expensive.

Petrochemical Service

1Cr-0.5Mo alloy is used in heater tubes and process piping that work at high temperatures. This alloy is suitable for petrochemical environments because it is resistant to corrosion and has good mechanical properties. Plants use these pipes when standard carbon steel cannot meet the service requirements.

Frequently Asked Questions

  • What temperature is A691 1CR rated for?

    A691 1CR is suitable for service temperatures up to 538°C (1000°F). This rating applies where oxidation and creep resistance are required.