Before pipeline commissioning, to what position should the variable spring on a spring-type hangar be set?

• A. Cold
• B. Hot
• C. Neutral
• D. Fully extended

Answer: (A)

Thermal movement is the key idea here. Pipelines change length as they heat up or cool down, and spring hangers are designed to absorb that movement so the pipe isn’t overstressed.

Setting the variable spring to cold during installation gives you a near-relaxed pre-load at ambient temperature. As the line heats during commissioning and operation, the pipe expands and the spring compresses further to take up that growth, keeping the load on the pipe consistent and preventing binding or excessive stress on supports.

If you set it hot, you’re preloading the hanger for operating temperature, which can cause over-tension when the pipe is cold. Fully extended leaves little room to absorb expansion, and neutral isn’t a defined, reliable starting point for this purpose.