If you have rung round for a quote on a gate, a railing or a rusty trailer chassis, you have probably heard welders mention TIG and MMA and wondered whether it actually matters. It does, but not always in the way people expect. Here is an honest breakdown of what each process does well, so you can tell whether the quote you are holding makes sense for your job.
MMA (manual metal arc, also called stick welding) uses a flux-coated rod that melts into the joint. It is rugged, works outdoors in wind and rain, and copes with painted, rusty or galvanised steel far better than the alternatives. That is why it is still the default for structural steelwork, gate hinges, fence posts and on-site repairs.
TIG uses a tungsten electrode and a separate filler rod, with argon shielding gas. It is slower and needs clean metal and shelter from draughts, but the control is far finer. It is the right choice for thin sheet, stainless steel, aluminium and anywhere the weld will be visible.
Neither is better overall. A welder who only offers one process will steer you towards it, which is worth bearing in mind when you compare quotes.
As a rough guide, the thickness and the finish decide it. Below about 2mm, MMA tends to blow through and TIG is the sensible option. Above 5mm or so, particularly outdoors, MMA is quicker and every bit as strong.
TIG is typically two to four times slower than MMA on the same length of weld, and the joint usually needs cleaning and fit-up beforehand. On a fabricated stainless handrail that is time well spent. On a gate that is getting galvanised and powder coated anyway, it is money spent on something nobody will ever see.
Most welding work in Kent is priced by the job or by the hour rather than by the process. Day rates for mobile welding in the Gravesend area commonly sit somewhere in the region of 300 to 500 pounds plus materials, depending on access, travel and whether power is available on site. A small mobile repair, say a gate hinge or a broken bracket, is more often a one to two hour visit. Anyone quoting a firm price without seeing photographs or the job itself is guessing.
Gravesend sits on the Thames estuary, and salt-laden air is unkind to steel. Exposed railings and gates along the riverside corrode noticeably faster than the same work a few miles inland. That pushes two decisions: use 316 grade stainless rather than 304 if you are going stainless near the water, and make sure mild steel fabrication is hot dip galvanised before painting rather than just primed.
Weather matters too. TIG needs still air, because a breeze strips the argon shield away and the weld goes porous and grey. On an exposed site on a windy day, a welder who insists on TIG outdoors without a decent screen is either inexperienced or in a hurry. MMA, by contrast, carries its own shielding in the flux coating and simply does not care.
One more practical point: if the work is on a structure that forms part of a building, a domestic extension steel or a balcony, for instance, it may fall under Building Regulations and require structural sign-off. Ask about that before work starts rather than after.
You do not need technical knowledge to sanity-check a quote. A few straightforward questions will tell you plenty about whether someone knows their trade.
No. On the same correctly prepared joint in mild steel, both will be stronger than the parent metal. TIG gives a cleaner, more controlled result on thin or visible work, but that is about precision and appearance rather than raw strength.
Yes, but only with wind screening in place, because even a light breeze disturbs the shielding gas and weakens the weld. If conditions are poor on the day, it is usually better to reschedule or work in a sheltered spot than to push on regardless.
It rules out TIG until the area is cleaned back to bare metal, which takes time. MMA handles less than perfect surfaces far better, which is why it is the usual choice for repairs to existing ironwork.
Tell Michael about your job. Drop a quick message with what needs welding, where it is and a photo if you have one. He will come back the same day.