Where lifting beams and spreader beams sit in a project

A lifting beam or spreader beam attaches below the crane hook to change how a load is supported. A lifting beam usually carries the load in bending and gives two or more attachment points at a fixed spacing. A spreader beam works mainly in compression and holds the sling legs further apart, which lowers the horizontal force pushed into the load. C-hooks, lifting frames and vacuum lifters belong to the same family of below-the-hook lifting devices.

These devices are rarely catalogue items when the load is a fabricated module, a precast element, a machine bed or a transformer. The device has to suit the centre of gravity of the load, the lifting points that already exist on it, and the headroom available under the hook. That is why they arrive at a contract manufacturer as drawings and a rated load rather than as a part number.

A fabricated lifting beam belongs to the same order type as other welded and machined machinery components made to customer drawings, which is the scope covered by Realjet's contract manufacturing service. What that scope does not include is setting the rated load of a lifting device or certifying its structural design. Those stay with the buyer's engineer.

Design responsibility stays with the buyer's engineer

A lifting device carries a load above people, so the design side and the build side of the purchase are best kept apart in the RFQ.

ASME B30.20 covers the marking, construction, installation, inspection, testing, maintenance and operation of below-the-hook lifting devices. Its design companion, ASME BTH-1, requires the device to be designed by, or under the direct supervision of, a qualified person, and it fixes the Design Category and Service Class that set the load factors and the fatigue assumptions. A fabrication workshop cannot read those two values off a general arrangement drawing.

The RFQ should therefore name:

  • the engineer or organisation that owns the design and the rated load calculation;
  • the Design Category and Service Class already selected;
  • the rated load and the load geometry used to establish it;
  • the conformity route the device has to satisfy in the market where it will be used, which differs between US practice under OSHA and the European requirements for non-fixed load lifting attachments in EN 13155.

If the buyer holds a drawing without a design basis, the design review comes before fabrication prices, not after.

Drawing and BOM inputs to send with the RFQ

A quotation for a welded beam is only comparable when the drawings and the basis of design are complete. Send:

  • a general arrangement drawing with datums, coordinate system and overall envelope;
  • detail drawings for every fabricated and machined item;
  • rated load, device self weight and the attachment points on both the crane side and the load side;
  • the hook interface, whether eye, clevis, shackle or hook pocket, with pin diameter and clearance;
  • span, headroom and the distance from the hook centre to the load;
  • material grades for plate, structural sections, pins and bushes;
  • the welding quality basis and the extent of non-destructive testing;
  • the proof load test requirement and the report format expected;
  • finish, colour and the exact marking text for the data plate;
  • the document pack required at handover.

Pin bores and bush seats deserve their own note. Their tolerance and surface condition decide whether the beam sits square on the load, and the drawing should state whether those features are machined after welding. Where the assembly uses purchased items such as shackles, swivels, rings or hooks, say who supplies them and which certificates they must carry. Fabrication scope normally covers fitting those items rather than making them.

Datum and tolerance language should follow one stated system. ASME Y14.5 or ISO 1101:2017 both work; mixing them inside one drawing set does not.

Welding, machining and material evidence

Weld quality becomes priceable only when the RFQ names a basis. Common choices for a steel lifting beam are AWS D1.1 for structural steel welding, or the ISO 3834 route, where ISO 3834-2:2021 sets comprehensive quality requirements for fusion welding. State the acceptance level, the extent of ultrasonic or magnetic particle testing, and any restriction on repair. Weld procedure and welder qualification records travel with the device.

Distortion matters more on a lifting beam than on a plain frame. Welding pulls the beam out of line, and a pin bore machined before welding can finish out of position. Two controls handle this in practice: a welding sequence with balanced passes and, where the drawing allows, finish machining of critical bores after welding. If the design calls for stress relief, say so in the RFQ so that bidders can price the furnace time.

Material certificates to EN 10204 3.1 for structural plate and pins complete the traceability chain, because the device serial number can then be tied to the heat numbers of the steel that carries the load. The material certificate and traceability guide sets out what those documents should contain.

Proof load test, marking and handover records

A custom-designed lifting accessory is proof tested before first use. The OSHA construction rule at 1926.251(a)(4) requires special custom design lifting accessories to be marked with their safe working loads and proof tested to 125 percent of rated load, and the 2004 OSHA interpretation on load testing and marking applies that reading to below-the-hook devices. The European route for non-fixed load lifting attachments works through verification by calculation and testing, with its own test factors and marking list.

The RFQ should settle five points about the test before prices arrive:

  • the test load and how its weight will be verified;
  • the test location, either at the fabricator's works or after installation;
  • who witnesses the test and signs the certificate;
  • whether a certificate and a marking record are issued for each device;
  • what happens to the test obligation after any repair or modification.

Marking follows the governing standard, and common practice is a permanent data plate carrying manufacturer identification, serial number, rated load and device weight, with the rated capacity also stencilled where site rules ask for it. That plate has to match the delivered documentation, because a mismatch between the two is what stops a device entering service.

Packaging, transport and site acceptance

Lifting beams are often longer than a standard container and heavier than they look. Agree the shipping frame, the lifting points that stay accessible in transit, and the protection for machined bores and painted faces. Where the design defines a centre of gravity, mark it on the device.

At site, someone has to confirm that the device arrived as tested and that the mark, certificate and serial number agree. Where the buyer adds or changes anything after delivery, from a new attachment point to a lengthened beam, both the design basis and the proof test need revisiting.

Comparing quotations on the same scope

Prices for these devices move with a handful of decisions rather than with steel weight alone: who owns the design, how much non-destructive testing is specified, whether critical bores are machined after welding, how the proof load test is arranged, and how much documentation is required. A bid that answers those points can be compared with another bid. A bid that quotes fabrication and painting only cannot.

Buyers who already hold an approved design, a rated load and a test specification can ask for the fabrication scope to be priced item by item. The welding procedure and NDT scope guide explains how to divide those records between buyer and supplier before the order is placed.