What is the difference between ASME B30.20 and ASME BTH-1?

ASME B30.20 is the safety standard covering marking, construction, installation, inspection, testing, maintenance and operation of below-the-hook lifting devices. ASME BTH-1 is the design standard it references, setting structural and mechanical design criteria through Design Categories and Service Classes.

What is a Design Category in ASME BTH-1?

Design Category A applies when loads and environment are predictable and defined, using a 2:1 design factor on yield. Design Category B applies when service conditions are less predictable or severe, using a 3:1 design factor on yield.

How often must below-the-hook lifting devices be inspected?

B30.20 calls for an inspection before each shift by the operator, plus periodic inspections at intervals set by service class and duty — typically yearly for normal service and more often for heavy or severe service.

Compliance Guide

ASME B30.20 and BTH-1 for below-the-hook devices

Two standards decide whether a lifting device is accepted on a North American site: B30.20 for safety, marking and inspection, and BTH-1 for design. Here is what each one covers, and what manufacturers and end users each have to produce.

Below-the-hook lifting beam handling steel plate in a fabrication shop

Scope

What each standard actually governs

The two are routinely confused. They are complementary, not alternatives — a device cannot be called compliant on the strength of one alone.

ASME B30.20 — the safety standard

Part of the B30 series. It governs how a below-the-hook lifting device is marked, constructed, installed, inspected, tested, maintained and operated in the field. It applies to structural and mechanical lifters, vacuum lifters, close-proximity operated lifting magnets, remotely operated lifting magnets, and scrap and material-handling grapples.

ASME BTH-1 — the design standard

Referenced by B30.20. It sets the structural, mechanical, electrical and fabrication design criteria the lifter must be engineered to, including allowable stresses, fatigue life and the Design Category and Service Class system.

How they work together

BTH-1 tells the manufacturer how to design the lifter. B30.20 tells the owner and operator how to mark, test, inspect and use it. A compliant device needs both: engineering evidence to BTH-1, and a marking, manual and inspection regime to B30.20.

BTH-1

Design Categories and Service Classes

Every BTH-1 lifter carries a Design Category and a Service Class. Together they set the design factor and the fatigue life the structure is engineered to — and they must be chosen from the real application, not copied from a catalogue sheet.

Design Category

Design Category A: Magnitude and variation of loads are predictable, loading and environment are accurately defined and not severe. Design factor of 2:1 on yield.
Design Category B: Magnitude and variation of loads are not predictable, or the environment is severe or not accurately defined. Design factor of 3:1 on yield.

Service Class (fatigue life)

Class 0: Up to 20,000 load cycles — occasional or one-off duty.
Class 1: 20,000 to 100,000 cycles.
Class 2: 100,000 to 500,000 cycles.
Class 3: 500,000 to 2,000,000 cycles.
Class 4: Over 2,000,000 cycles — continuous production duty.

Required marking

B30.20 requires durable marking on the lifter itself. Missing marking is the most common reason a new imported device is rejected on arrival.

Manufacturer's name and address
Serial number and model or lifter identification
Lifter weight (when over 100 lb / 45 kg)
Rated load
ASME BTH-1 Design Category
ASME BTH-1 Service Class
Cold current amps and rated voltage, for magnets

Owner and operator duties

Compliance does not end at delivery. B30.20 places ongoing obligations on the company using the device.

Keep the manufacturer's operating, inspection and maintenance manual on file
Run an operator inspection before each shift
Run frequent and periodic inspections on intervals matched to service class and duty
Record periodic inspections in dated, signed reports
Remove damaged, altered or unmarked lifters from service until re-rated or repaired
Re-test after structural repairs, alterations or a change in rated load

Canada

What changes for Canadian sites

Manufacturers entering Canada usually meet compliance questions before they meet price questions. These are the four issues that come up most often.

CSA and provincial occupational health and safety regulations govern use in Canada; several provinces reference the ASME B30 series directly.
Engineering documentation may need to be reviewed or stamped by a professional engineer licensed in the province of use.
Imported devices designed to EN or ISO rules usually need a BTH-1 design review, revised marking and English-language manuals before they are accepted on Canadian sites.
Proof-load test certificates should follow the device from the factory, not be recreated after arrival.

This guide is a plain-language summary for planning purposes. Always work from the current published editions of ASME B30.20 and ASME BTH-1 and the regulations of the province where the device will be used.

Below-the-hook devices Optional features available

Need a device brought into compliance for Canada?

We work with manufacturers on BTH-1 design review, marking, manuals and test documentation so equipment is accepted the first time it reaches site.

Discuss Compliance