If you’re buying welding or fabrication work that involves pressure, the terms can get confusing fast. Pressure welding, B pressure, process piping, pressure vessels and skids all get mentioned in the same conversation, and they overlap. This guide explains what each one means, how they connect, and what to ask before you hire a shop. It’s written for plant managers, contractors and project owners in Calgary and across Alberta.
What is pressure welding?
In everyday shop talk, “pressure welding” means welding on equipment that holds or carries fluid or gas under pressure. That includes boilers, pressure vessels and pressure piping. A failed weld on a pressure system can release stored energy suddenly, so the work is held to a higher standard than ordinary structural welding.
In Alberta, this work is regulated under the provincial Safety Codes Act, and ABSA (the Alberta Boilers Safety Association) administers pressure equipment safety. Welders who work on pressure equipment need the right ABSA certification, and the qualification has to match the job. The exact rules depend on the type of equipment, so it’s always worth confirming the requirements for your specific project.
What is B pressure welding?
“B pressure” refers to the Grade B pressure welder certificate issued in Alberta. According to ABSA’s Grade B information, candidates are generally journeyman or Red Seal welders, or third-year welding apprentices applying through their school.
The certificate works together with a performance qualification card. The card lists what the welder is actually authorized to do, such as the welding process, materials and limits on the work. In other words, holding a B ticket isn’t a blanket approval. What matters is whether the welder’s card covers your specific weld. Learn more on our B pressure welding services page.
Pressure piping: moving fluids and gases safely
Pressure piping is the network of pipe that carries steam, gas, oil, chemicals and other process fluids. In shops it’s often built as pipe spools: sections fabricated in a controlled shop environment and then installed and connected on site. Fabricating spools in the shop generally makes it easier to control weld quality and testing.
ABSA notes that ASME B31.3, the process piping code, is adopted in Alberta for process piping where it applies. Piping construction in the province also typically involves registered welding procedures, pressure testing (commonly hydrostatic testing) and documentation of the finished work.
Different welding processes are used depending on the pipe and the job. If you’d like a plain-language overview, see our guides to TIG (GTAW) welding and stick (SMAW) welding. For the full service, visit our high-pressure process piping fabrication page. Stainless piping has its own requirements, covered on our stainless steel welding page.
Pressure vessel fabrication
A pressure vessel is a closed container that holds gas or liquid at a pressure different from the surrounding air. Air receivers, separators and heat exchanger shells are common examples. Because the contents are under pressure, vessels are built to recognized design codes, most commonly ASME Section VIII, Division 1 or CSA B51.
Alberta also requires pressure vessel designs to be registered, and ABSA’s guidance says the submitted drawings need to show the design conditions and loadings. That step happens before the vessel is built, which is why it pays to bring your fabricator in early. Our pressure vessel fabrication services page covers what we build.
Structural skids and skid packages
A skid is a steel frame that carries equipment so it can be built, moved and installed as one unit. Pump skids, compressor skids and generator skids are common. A skid package goes a step further, combining the frame with equipment, piping and sometimes vessels, so the customer receives a complete assembly.
This is where the topics in this guide meet. The steel frame is structural work. Any pressure piping or vessels mounted on the skid fall under the pressure equipment rules above. Building both together in one shop can simplify coordination. See our oil field skid packages page, and our structural beam, column and truss fabrication page for the structural side.
How it all fits together
| Topic | What it is | Key thing to know |
|---|---|---|
| Pressure welding | Welding on equipment that contains pressure | Regulated in Alberta; welder certification must match the job |
| B pressure welding | Grade B pressure welder certification | Works with a performance qualification card |
| Pressure piping | Pipe systems carrying fluids and gases | Built to piping codes; tested and documented |
| Pressure vessels | Closed containers holding pressure | Built to vessel codes; design registration in Alberta |
| Structural skids | Steel frames carrying equipment | Often combine structure, piping and vessels |
Questions to ask before hiring a fabricator
Whoever you choose, these questions help you compare shops fairly:
- Do the welders’ certifications and qualification cards cover the process and material for my job?
- Which codes will the work be built to, and who handles registration and documentation?
- What inspection and testing will be done, and what paperwork will I receive at the end?
- Can the work be done in the shop, on site, or both?
- Who coordinates the structural, piping and vessel work if they’re all part of one package?
Requirements vary by project and equipment type, so treat this guide as an overview. For the definitive rules, check with ABSA or ask your fabricator to walk you through them.
Shop work and on-site work
Many pressure jobs mix both. Spools, vessels and skids are commonly built in the shop, while tie-ins, repairs and modifications happen at the facility. If you’re working on an oilfield site, see our rig welding services, and for repairs at your location, our mobile welding repair service.
Talk to us about your project
If you’re planning pressure piping, a vessel, a skid or repair work in Calgary or southern Alberta, we’re happy to talk it through. Visit the Fabrication Pros homepage to see all our services, or contact us for a free quote.
Contact us with any questions you may have.
