Rigging, Hangers, and Supports Flashcards

A pipe hanger rod is installed at a 15° angle from vertical due to a structural conflict. If the vertical load on the hanger is 800 lbs, what is the approximate tension in the angled rod?

Answer: 828 lbs

When a hanger rod is angled from vertical, the tension in the rod is greater than the vertical load. The tension equals the vertical load divided by the cosine of the angle: 800 / cos(15°) = 800 / 0.966 ≈ 828 lbs. Ignoring this angular correction is a common field error that can lead to undersized rod selection.

When specifying a variable spring hanger for a high-temperature steam line, the 'cold load' and 'hot load' differ. Which condition governs the hanger rod and structural attachment sizing?

Answer: The greater of the two loads, regardless of which condition produces it

Hanger rods, structural attachments, and building steel must be sized for the greater of the cold or hot load. Although variable spring hangers are designed to accommodate both conditions, the maximum load — which may occur in either the installed (cold) or operating (hot) position — determines the structural capacity required. Designing only for hot load can leave the structure undersized during hydrostatic testing or cold startups.

A four-leg bridle sling with a 60° horizontal sling angle (30° from vertical) is used to lift a pipe assembly weighing 4,000 lbs. Assuming equal load distribution, what is the approximate load on each sling leg?

Answer: 1,155 lbs

With four legs sharing the load equally, each leg carries 4,000 / 4 = 1,000 lbs vertically. However, the actual tension in each sling leg must account for the sling angle: tension = vertical share / sin(sling angle from horizontal) = 1,000 / sin(60°) = 1,000 / 0.866 ≈ 1,155 lbs. The shallower the sling angle, the higher the tension — a critical rigging safety concept.

MSS SP-58 designates hanger types by number. Which type designation describes a 'Riser Clamp' used to support the weight of a vertical pipe at each floor level?

Answer: Type 36

Per MSS SP-58, Type 36 is the standard riser clamp used to support vertical pipe (risers) at floor penetrations. It clamps around the pipe and bears on the floor sleeve or structure. Types 1 and 2 are clevis and beam clamp hangers for horizontal pipe, and Type 8 is a carbon or alloy hanger rod coupling. Knowing MSS SP-58 type numbers is essential for specifying and procuring pipe supports correctly.

A pipefitter is installing a constant-support (constant effort) hanger on a large-bore steam main. During installation, the travel indicator shows the hanger is set at the 'cold' position but is already at the bottom of its travel range. What is the MOST likely cause and correct action?

Answer: The unit was sized for insufficient travel range; replace with a hanger sized for the actual thermal travel of this line

A constant-support hanger bottomed out at the cold position means the unit's travel range is shorter than the actual thermal displacement of the pipeline. This is a sizing error — the unit must be replaced with one that accommodates the full cold-to-hot travel. Simply using a stiffer spring or adjusting the indicator does not solve a travel-range deficiency and could result in the hanger providing no support at the hot position, overloading adjacent supports.

When using a come-along (lever hoist) to laterally position a heavy pipe spool before welding, the rigger notices the load chain has a visible twist in it. What is the correct action?

Answer: Stop immediately, lower the load to the ground, and remove the twist before re-rigging

A twisted load chain in a lever hoist is a critical defect that must be corrected before any lifting or tensioning operation continues. Twists cause uneven stress distribution across the chain links, drastically reduce the rated capacity, and can cause sudden chain failure. The load must be set down safely and the chain fully untwisted and inspected before re-use. No percentage-based reduction in rated load is a recognized safe workaround for a twisted chain.