Q1: Why are seamless pipes preferred for high-pressure boilers?
A: No weld seam means uniform strength and no weak point. Seamless tubes (A192, A210) withstand repeated thermal cycling and high internal pressure better than welded -5-7.
Q2: Can seamless carbon steel pipe be used for hydrogen service?
A: Yes, but material must be controlled for hardness and free from cold work. Grades like A106 Gr.B with proper heat treatment are commonly used. Avoid high residual stress.
Q3: What grade is recommended for hydraulic cylinders?
A: Cold-drawn seamless precision tubes (e.g., DIN 2391 St52.0, EN 10305-1). High surface finish (Ra ≤ 0.4 µm), tight ID tolerances for skiving & roller burnishing -4.
Q4: Is A106 Gr.B suitable for sour service?
A: Standard A106 Gr.B is not NACE-compliant. For sour service, request A106 Gr.B with NACE MR0175, requiring hardness ≤ 22 HRC and controlled sulfide stress cracking tests -10.
Q5: What is the difference between T22 and P22 pipe?
A: T22 is for small diameter tubes (boilers/superheaters) , P22 is for large diameter piping (headers) . Both are 2.25% Cr-1% Mo alloy steel, high-temp service -7.
