Class Code 3620
Boiler Mfg; Plate Steel Products Fabrication
Class 3620 covers shop-based manufacturing of boilers, pressure-vessel components and fabricated plate-steel products — from plate cutting and rolling to welding, assembly and pressure testing. The approved pure premium rate for California effective September 1, 2026 is $6.620 per $100 of payroll, a key input to your workers' comp cost for these higher-hazard metal fabrication operations.
What Class Code 3620 Covers
This classification applies to employers whose primary operations are fabricating boilers, pressure vessels and plate-steel products in a shop or plant. Typical activities include cutting and shearing plate, rolling and forming, fit-up and tack welding, full welding and grinding, machining and drilling for attachments, assembly and rivet or bolt work, hydrostatic or pneumatic pressure testing, heat treatment and final finishing. Work performed on a fixed shop floor with shop tools, cranes and presses falls here; field erection or installation at customer sites is generally handled under different classifications. The code covers production employees, shop supervisors who perform hands-on work, and support workers directly involved in the fabrication process.
Who It Applies To
- Boiler and pressure-vessel manufacturers producing shop-built units
- Heavy plate-steel fabrication shops making structural or industrial components
- Manufacturers of tanks, vats and large industrial vessels
- Fabrication divisions of industrial equipment manufacturers
- Shops performing plate cutting, rolling, welding and assembly
Common Job Duties
- Cutting plate with plasma, oxy-fuel or shears
- Plate rolling, forming and edge preparation
- Fit-up, tack welding and full welding (SMAW, GMAW, FCAW)
- Grinding, beveling, machining and drilling for attachments
- Rigging and moving heavy plate with cranes and hoists
- Hydrostatic or pneumatic testing and inspection of vessels
- Heat treatment, surface finishing and nondestructive testing
Common Injury Risks
Understanding the $6.620 Rate
The pure premium rate of $6.620 per $100 of payroll represents the insurer's estimated loss cost for claims before insurer expenses, profit and any adjustments. To calculate base premium, multiply your payroll for class 3620 by the rate and divide by 100; insurers then add expense loads, apply your experience modification and any credits or debits. Final premium is affected by your company-specific loss history, payroll accuracy, claim severity, safety controls and participation in group-rating or loss-sensitive programs.
Cal/OSHA Compliance Requirements
Cal/OSHA Title 8 standards most relevant to this work include requirements for welding, cutting and brazing (hot work controls and permits), machine guarding, lockout/tagout for equipment servicing, cranes and hoists for material handling, noise and respiratory protection, hazard communication for chemicals and permit-required confined space procedures for vessel entry. Employers must implement written programs (respiratory protection, hearing conservation, hot work permits, LOTO and confined space) and provide training and PPE specific to welding fumes, metal dust and heavy-material rigging.
How Key HR Helps Employers Under Class Code 3620
A PEO like Key HR helps employers with class 3620 by ensuring correct payroll classification, administering tailored safety programs (welding fume controls, LOTO, confined-space entry, rigging training) and coordinating Cal/OSHA-compliant written programs. Key HR also handles claims management and return-to-work coordination to reduce claim duration, and can pursue group-rating or loss-sensitive options to lower workers' comp costs over time.
Get a QuoteFrequently Asked Questions
Does Class 3620 include on-site installation or erection of boilers?
No. Class 3620 is intended for shop-based fabrication of boilers and plate products. Field erection or installation, where employees work at customer sites or perform erection and piping, is typically classified under a different code because the exposures and risks differ.
What practical steps reduce workers' comp costs for plate-steel fabrication shops?
Focus on engineering controls (mechanical lifting, fume extraction), robust lockout/tagout and hot work permit programs, PPE and hearing/respiratory protection, preventive maintenance on cranes and presses, pre-shift inspections, and a formal light-duty/return-to-work program to limit claim costs and experience-mod impacts.
Are welders and crane operators classified separately from fabricators?
Payroll is usually assigned based on the primary operations of the business, but in some cases distinct job functions with materially different exposure profiles can be assigned to different codes. Accurate payroll reporting and documentation at audit time is essential; a PEO can help ensure correct classification and defensible audit records.
Quick Facts
- Class Code
- 3620
- Classification
- Boiler Mfg; Plate Steel Products Fabrication
- Pure Premium Rate
- $6.620 / $100 payroll
- Effective Date
- September 1, 2026
- Source
- WCIRB Approved Filing
Manage Workers' Comp Through a PEO
Key HR provides pay-as-you-go workers' comp for California employers — no large deposits, no audits, better rates.
Get a Quoteor call (800) 922-4133Ready to Simplify Workers' Comp for Class Code 3620?
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