Not Every Broken Part Is Steel

A lot of commercial welding repair starts with a phone call that goes something like this: a part broke, it's metal, can it be welded? Often the honest answer is yes. But the next question matters more than many people expect. What kind of metal is it?

Mild steel is the forgiving one. Cast iron, aluminum and stainless steel each weld differently, and a repair that ignores the difference can look fine on the day and crack a week later. Cast iron repairs in particular have a reputation for that.

At A.G. Welding, our commercial welding repair work covers steel, cast iron, aluminum, cast aluminum and stainless steel, in our shop or on site.

What we've found over nearly 40 years of welding in Houston is that knowing the material before anyone strikes an arc is what separates a lasting repair from a temporary one.

Cast Iron Repairs and Other Metals: What Changes

Here is the short version for property managers, facility staff and GCs who are deciding whether a broken part is worth sending out.

Cast Iron

Cast iron shows up in older equipment housings, pump and valve bodies, machine bases, decorative castings and some ornamental fence and gate parts. It holds a lot of carbon, which is what makes it brittle. Heat it fast and cool it fast, and the area around the weld can harden and crack.

Cast iron repairs are usually done with controlled heat. The part is preheated, welded with a filler suited to cast iron (nickel-based rods are common), and allowed to cool slowly. Sometimes brazing is the better choice. Grey cast iron and ductile cast iron behave differently too, so the repair plan depends on which one is on the bench.

Aluminum and Cast Aluminum

Aluminum carries heat away fast and forms an oxide skin that has to be cleaned off before welding. It's typically welded with TIG equipment set up for aluminum. Cast aluminum adds porosity: older castings often hold oil, paint or trapped gas that bubbles up into the weld unless the part is cleaned thoroughly first.

Cast aluminum is common on ornamental commercial fences and gates, light pole bases, signage brackets and equipment covers.

Stainless Steel

Stainless welds well, but it's fussy about contamination and heat. Tools and wire brushes used on carbon steel can leave particles that rust on a stainless surface later. Too much heat can discolor it and reduce its corrosion resistance near the weld, which matters on food service equipment, handrails and anything exposed to the weather.

Repair or Replace

The material is one part of the decision. A few other questions usually settle it:

• Is the part still made? An old casting with no replacement available is often worth repairing even if the repair takes time.
• What does the part do? A decorative casting and a load-carrying bracket get very different scrutiny. Anything structural, or anything holding people or equipment, may need an engineer's say before it's repaired.
• How much of it is damaged? A clean crack in one place is a good repair candidate. A part corroded through in several spots usually isn't.
• Can it come to the shop? Shop repairs are generally less expensive than on-site work, and controlled heating is easier on a bench than in a parking lot.
• What will it cost the operation to wait? Sometimes a quick repair keeps a gate, a door or a machine working while a replacement is ordered.

Getting a Good Repair

The best thing a property manager or GC can do is send clear information up front: photos of the break, the part from a few angles, any markings or part numbers, and what the part does. That's usually enough to say whether it's cast iron, aluminum or steel, whether shop or field repair makes more sense, and whether the part should be replaced instead.

How A.G. Welding Handles Material Repairs

A.G. Welding repairs steel, cast iron, aluminum, cast aluminum and stainless steel parts for commercial properties across the Houston area, in our shop or on site. We'll look at the part, tell you plainly whether it's worth repairing, and do the repair to suit the metal.

Contact A.G. Welding to discuss a broken cast iron, aluminum or stainless part by requesting a free estimate or calling us at (713) 988-4200.