Pipe Hanger and Support Fabrication and Installation

Pipe Hanger and Support Fabrication and Installation

Pipe systems aboard a vessel carry fuel, seawater, freshwater, hydraulic fluid, exhaust, and bilge drainage. Every pipe run must be held firmly in place so vibration, thermal expansion, and vessel motion cannot overstress joints or bulkhead penetrations. Pipe hangers and supports transfer the pipe load to the ship's structure, and they must be fabricated and installed exactly where the design drawing says — at the right frame location, at the right height, and plumb and level within tight tolerances.

Types of Hangers Used in Marine Work

Clevis hangers consist of a U-shaped clevis fitting that cradles the pipe, a threaded rod that carries the load upward, and a top fitting or welded bracket anchored to the overhead or a web frame. The clevis pin can be removed to drop the pipe clear during maintenance. Clevis hangers are the most common hanger type for below-deck piping on steel vessels.

U-bolt hangers use a bent-rod U shape that wraps around the pipe; the two threaded legs pass through a steel saddle plate and are secured with nuts. U-bolts grip the pipe more rigidly and are often used where vibration is higher or where the pipe must be prevented from moving laterally as well as vertically.

Both types may be used together on a single pipe run when the drawing calls for it, as each offers different restraint characteristics.

Reading the Drawing and Transferring Locations

Before drilling or welding anything, read the isometric or orthographic pipe drawing completely. Locate the following for every hanger:

• Frame number or reference dimension from a baseline
• Height of the pipe centerline above the deck or below the overhead
• Hanger type and hardware size
• Maximum support spacing (a maximum distance between hangers is always stated; never exceed it)

To transfer a hanger location from the drawing to the actual hull frame, use a tape measure to find the correct frame bay, then use a plumb bob dropped from the overhead or a level extended from the frame flange to establish the exact vertical line at which the bracket will land. Mark the drill center with a center punch before drilling — this prevents the bit from walking.

Fabricating the Bracket and Assembly

For a welded flat-bar bracket, cut mild steel flat bar to the length shown on the detail drawing using a bandsaw or cutoff wheel. Deburr all edges with a file or grinder. Lay out and center-punch hole locations for the threaded rod and for the frame attachment bolts. Drill a pilot hole first — typically 1/8 inch smaller than the finish diameter — then step up to the finish drill size. This two-step process produces a cleaner, rounder hole in steel and reduces drill breakage.

A threaded insert welded into the bracket provides the anchor point for the threaded rod. Position the insert, tack-weld in two places, confirm it is square to the bar using a small square, then complete the weld passes. Allow the weld to cool before threading in the rod to avoid heat damage to the threads.

Inspect the completed assembly against the shop drawing before installation: check overall length, hole location, weld quality (no visible cracks or porosity), and thread engagement.

Installing and Torquing the Hanger

Offer the bracket up to the web frame at the marked location. Use a combination level or plumb bob to confirm the bracket face is plumb — the allowable deviation in this shop is 1/8 inch over the bracket height. Clamp or hold the bracket while a partner verifies plumb, then drill through the frame flange at the marked centers using a portable drill. Install fasteners, run nuts up finger-tight, recheck plumb, then torque to the specification shown on the drawing or in the hardware manufacturer's table. Use a calibrated torque wrench, apply steady increasing force — do not jerk — and stop the moment the wrench clicks or the pointer reaches the target value. Record the torque value and fastener size on the inspection record form.

Thread the clevis hanger rod to the correct height so the pipe centerline will land at the elevation shown on the drawing. Height tolerance in this exercise is ±1/4 inch. Hang the pipe spool, lock the clevis pin, and make a final plumb check.

For the U-bolt, slide the U over the pipe, pass the legs through the saddle plate, and tighten the nuts evenly — alternate from side to side in small increments — until the specified torque is reached. Uneven tightening cocks the U-bolt and can ovalize thin-wall pipe.

Safety

• Eye and face protection is required at all times during drilling and welding. Flying chips from drill operations are a leading cause of eye injury in the shop.
• Wear welding PPE — helmet, leather gloves, flame-resistant clothing, and steel-toed boots — whenever the MIG welder is energized.
• Apply lockout/tagout procedures on the drill press before changing bits or clearing a jam. Follow your shop's written LOTO procedure.
• When working overhead to install a bracket, secure all tools with lanyards or set them in a tool bag — a dropped drill or wrench at head height can cause serious injury.
• Inspect the torque wrench calibration date before use. An out-of-calibration wrench can produce under- or over-torqued joints; report any wrench that shows damage or is past its calibration due date.

Completing the Inspection Record

Every hanger installation must be documented. The inspection record form captures: hanger type, location (frame number), pipe size, installed height (measured), torque value applied, plumb reading, and the signatures of the student and the instructor. An incomplete or unsigned record is a failing result regardless of how good the physical work is — the same standard applies in commercial shipyards, where traceability of every installed system is a quality requirement.