Pipefitter definition
A pipefitter is a skilled tradesperson trained to lay out, fabricate, install, and maintain piping systems that carry high-pressure steam, gases, chemicals, petroleum products, and other fluids in industrial and commercial facilities. Pipefitters work to applicable piping codes — most commonly ASME B31.3 for process piping and ASME B31.1 for power piping — which govern material selection, joint design, testing requirements, and documentation.
The Bureau of Labor Statistics classifies pipefitters alongside plumbers and steamfitters under SOC code 47-2152. However, industrial pipefitters are a distinct specialty with different training, different certification requirements, and significantly higher compensation than residential or commercial plumbing work.
What do pipefitters do?
- Layout and fabrication: Reading isometric drawings, measuring and cutting pipe, threading or beveling for welding, and prefabricating pipe spools in a shop environment for field installation.
- Installation: Hanging pipe with proper support spacing, connecting flanged and welded joints, installing valves, gauges, and instrumentation connections.
- Hydrostatic and pneumatic testing: Pressure testing completed piping systems to verify integrity before commissioning. Documenting test results per code requirements.
- Maintenance: Valve packing replacement, flange leak repair, expansion joint replacement, and piping system modifications during planned and unplanned outages.
- Shutdown and turnaround work: Intensive maintenance and modification work during planned facility outages. The highest-compensated segment of pipefitter work.
Pipefitter vs. plumber: what is the difference?
A plumber primarily installs and repairs sanitary (drain, waste, vent), potable water, and gas piping systems in residential and light commercial buildings. A pipefitter works on industrial process piping systems carrying high-pressure steam, chemicals, petroleum products, and gases in refinery, power plant, pharmaceutical, and chemical plant environments. The pressure levels, material specifications, code requirements, and safety stakes are fundamentally different between the two trades.
The practical distinction matters for staffing agencies. A licensed plumber cannot be placed on ASME B31.3 process piping work at a refinery — they do not hold the required procedure qualifications and would not pass a facility qualification test. Clients who ask for a "plumber" but actually need an ASME-qualified process pipefitter are a common source of placement failures at agencies that do not understand the distinction.
What certifications do industrial pipefitters hold?
- ASME B31.3: The process piping code. Governs piping in refineries, chemical plants, pharmaceutical facilities, and other industrial process environments. Most common certification requirement for industrial pipefitter placements.
- ASME B31.1: The power piping code. Governs boiler feedwater, steam, and condensate piping in power generation facilities.
- NCCER Pipefitter Level 4: The standardized industrial pipefitter journeyman curriculum. Appropriate for general industrial plant work that does not require specific code qualifications.
- UA Journeyman: The United Association of Plumbers and Pipefitters union journeyman credential. Required for dispatch through UA locals in union-organized markets.
For state-level market context and marketing guidance for agencies placing pipefitters, see pipefitter staffing agency SEO. For salary data, see the pipefitter salary guide. For hiring guidance, see how to hire pipefitters.