Piping Piping Materials and Specifications

Question 1

What does the ASTM designation 'A106 Grade B' specify for pipe?

Accepted Answer

Seamless carbon steel pipe for high-temperature service

Answer

ASTM A106 Grade B is a seamless carbon steel pipe specification commonly used in high-temperature process piping up to 750°F (399°C).

Question 2

What is the primary advantage of using austenitic stainless steel (e.g., 316L) over carbon steel in piping?

Accepted Answer

Superior corrosion resistance, especially in chloride and acidic environments

Answer

Austenitic stainless steels like 316L offer excellent corrosion resistance due to their chromium and molybdenum content, making them suitable for corrosive process fluids.

Question 3

What is the purpose of the ANSI/ASME pipe schedule number system?

Accepted Answer

To indicate the pipe wall thickness relative to the outside diameter

Answer

Pipe schedule numbers (Sch 40, Sch 80, etc.) define the wall thickness as a ratio, where higher schedule numbers indicate thicker walls for higher pressure service.

Question 4

What does 'NPS' stand for in pipe specifications?

Accepted Answer

Nominal Pipe Size

Answer

NPS (Nominal Pipe Size) is a dimensionless designator that approximately indicates pipe size; actual OD does not equal NPS for sizes 14 inches and below.

Question 5

Which material is preferred for piping in hydrogen service to minimize hydrogen embrittlement?

Accepted Answer

Austenitic stainless steel or specially treated low-alloy steel per Nelson curves

Answer

The Nelson curves (API 941) guide material selection for hydrogen service by identifying safe operating limits for carbon and low-alloy steels to avoid high-temperature hydrogen attack.

Piping Practice Test

Piping Practice Test

Piping Piping Materials and Specifications