The short answer: if the thing can’t move, or moving it costs more than the weld, mobile welding is the call. If it travels easily and needs tight tolerances, bring it to the shop. Most real jobs use both. Parts get built on the bench and installed on site by the same crew.
We run a fabrication shop at 3555c First St, Livermore, CA 94551 and two fully equipped mobile rigs. So we don’t favor either one. This is how we sort jobs between them for contractors, fleet operators and facility managers across the East Bay.
Start with whether the part can move
An excavator with a cracked boom, a steel column holding up a mezzanine, a pipe run inside a mechanical room, structural steel inside a working port terminal. None of those are going anywhere. Mobile welding exists for exactly this work.
Federal safety rules lean the other way when there’s a choice. Under OSHA’s construction fire prevention standard, 29 CFR 1926.352, objects to be welded or cut should be moved to a designated safe location when practical. If they can’t be moved, everything flammable that can be moved has to be cleared out or protected, an extinguisher has to be on hand, and a fire watch is required when normal precautions aren’t enough. None of that stops field work. It just means field work carries setup the shop doesn’t.
So the first question is simple. Can it go in a truck without a crane, a permit or a day of teardown? If not, the rig comes to you.
When mobile welding is the right call
Downtime usually settles it. Trailering a machine to a shop costs a day each way plus transport, and on a rental fleet those lost days are often worth more than the repair. That’s why our heavy equipment welding happens at the machine, including the machining. Our rigs carry line boring gear, so a worn joint gets restored in the yard instead of at a machine shop. Line boring worn pins and bores walks through that repair.
Mobile welding is also the answer when:
- The steel is already standing. Reinforcement, member replacement and modification on an existing structure happen in place, which is a big part of our structural steel fabrication work.
- The operation can’t stop. Port and municipal work gets sequenced around the facility, the way our maritime and municipal structural welding was done at the Port of Oakland with zero disruption to port operations.
- Something broke and it’s in the way. Trailer frames, gates, tanks and cracked housings are everyday welding repair calls, and emergency calls are welcome.
- The pipe has to be welded where it runs. Tie-ins and repairs to existing lines happen in place.
When the shop bench wins
A shop controls things a jobsite can’t. Parts get clamped in fixtures, turned so every weld is made flat or horizontal instead of overhead, and cut and fit with shop tools. Wind doesn’t blow the shielding gas away. Tight tolerances are easier to hold.
New work usually starts on the bench. Custom gates, railings, guards, brackets, skid frames and one-off parts are built in the shop and then installed, which is how our custom metal fabrication runs. Pipe spools that can be prefabricated get welded in Livermore and set in the field, which is how most of our stainless steel pipe welding starts. Small attachments, a bucket thumb or a quick coupler, often come out better on the bench than welded on a machine parked on a slope.
Permits and inspections cover the shop too
People sometimes assume shop work skips the paperwork. For structural steel it doesn’t. Chapter 17 of the California Building Code requires special inspection of structural steel welding for shop fabrication and field work alike. In Oakland, shop welding still needs a special inspector at the fabricator’s facility unless the shop is an Approved Fabricator under CBC 1704.2.5, and welding inspection there is continuous, so the inspector is present for the work.
Field work adds the hot work permit, and every city handles it differently:
- Livermore: the Livermore-Pleasanton Fire Department wants the hot work application 14 days ahead and the inspection scheduled 48 hours ahead.
- Oakland: hot work is an annual operational permit from the Oakland Fire Department. The fee schedule effective July 1, 2025 put fire operational permits at $381 to $1,051 a year depending on category.
- Hayward: the Fire Department issues an annual cutting and welding permit, $1,051 in the city’s FY 2025-26 fee schedule, and approves a designated area rather than the whole site.
Many industrial sites already hold these permits. Ask whether yours covers the spot where the work will happen, and tell us early so we schedule around the lead time instead of discovering it the morning the rig shows up.
Most jobs use both
The best answer is usually a split. Fabricate the components on the bench, where tolerances are easiest to hold, then send the rig to handle fit-up and installation. When one contractor does both halves under one license, there’s no gap between the fabricator and the installer to argue across when a part doesn’t fit.
Bucket work is a good example. A worn bucket might get its edges rebuilt and hard-faced at the machine, while a replacement bracket for the same excavator gets built on the bench from the failed original and brought out on the same visit.
What does mobile welding cost?
For on-site work we use a 4-hour industrial minimum of $600. It covers a full crew and a properly equipped rig, which is what keeps the quality consistent. Beyond that, it depends. Access, material and the amount of prep the damage needs set the price.
Compare the whole bill. Not the hourly rate. A shop job looks cheaper until you add the tow, the teardown, the day the machine isn’t working and the reinstall. A field job looks pricier until you notice nothing had to be moved. For a small one-off fix that doesn’t justify the minimum, we’ll tell you so. Bundling several repairs into one visit is usually the better deal.
Tell us about the job
Send the dimensions, the material, where it sits, and a photo. That’s enough. It tells us whether it’s a rig job, a bench job or both, and lets us show up with the right process, filler and gas. HRT Mobile Welding is a C-60 licensed welding contractor, license #1132921 (you can check it with the CSLB), with AWS certified welding specialists and full insurance.
Call (925) 518-6694 or request a quote online. Drop-offs go to the shop at 3555c First St, Livermore, CA 94551, Monday through Friday, 7:00 AM to 5:00 PM. The rigs cover Oakland, Hayward, Fremont, Walnut Creek, Tracy and the rest of our East Bay service area. Our home page has recent project examples.