Welding on a ship is not the same activity as welding in a workshop ashore. The vessel moves. The ventilation is restricted. The combustible materials are nearby. The work is being done by crew or contractors who may not have the spec sheet for the parent metal. The supervision chain is real but not quite as immediate as on a controlled industrial site. All of this means hot work on board needs more discipline, not less.
For vessels at Chennai Port, welding work is sometimes done by ship's crew for routine repairs and sometimes by specialist contractors for larger jobs - tank repairs, structural work, dry-dock-pre-work. Both paths run through the same procedural framework.
The hot work permit is the operational gate
Before any welding, cutting, or grinding starts, a hot work permit must be raised. The permit specifies the location, the work to be done, the gas-free verification (where applicable), the fire watch arrangement, the ventilation, and the time window. It is signed by the responsible officer, the person doing the work, and the master.
This is not bureaucracy. The permit forces the discussion that prevents the most common hot work incidents - cutting into a tank that has not been gas-freed, igniting hidden combustibles in adjacent spaces, working without immediate fire-watch coverage. Skipping the permit is the leading factor in serious shipboard fires from hot work.
Welder qualifications and process selection
Marine welding requires welders qualified to the relevant code - usually AWS, ASME, or IACS standards depending on the application. The qualification certifies the welder for specific processes (SMAW, GMAW, TIG), specific positions, and specific material types. A welder qualified for general structural work in carbon steel is not automatically qualified for stainless or aluminium.
For class-survey-relevant work - hull plate repairs, structural members, pressure-vessel piping - the welder qualification, the procedure qualification record, and the inspection regime all need to be documented. Class society surveyors can and do refuse work that does not have the supporting documentation, even if the visible weld looks acceptable.
Consumables and the chandler's role
Welding consumables - rods, wire, gas, tungsten electrodes - need to match the parent metal. SMAW rods are coded by AWS classification (E6010, E7018, E316L for stainless, etc.) and the right rod for the job depends on the metal being welded, the position, and the service requirements. Stocking the right consumables in the right quantities is part of the chandler's supply role for vessels with active welding inventories.
Shielding gas - argon, CO2, mixed gases - is supplied in cylinders at Indian ports against the welding process being used. Gas cylinder logistics include the empty-cylinder return as well as the supply, which the chandler typically coordinates.
Tank-side hot work specifically
Hot work on or near tanks - whether the tank is for cargo, ballast, or fuel - is the highest-risk category. Gas-free certification is mandatory before any hot work starts. The certification is issued by a qualified gas-free tester after measurement of hydrocarbon vapour, oxygen, and toxic gas concentrations. The certificate is valid for a defined period, typically 8-12 hours, after which the test must be repeated.
For cargo tanks on tankers and chemical carriers, the gas-free process can take days, especially for residues from heavy crude or chemical cargoes. Vessels planning hot work on tanks should give themselves time, not optimism.
Fabrication for spares and modifications
Some shipboard fabrication is genuinely engineering work - new brackets, modified piping, custom protective frames. Others are improvised solutions to problems no one anticipated. For vessels at Chennai with extended port stays, fabrication work can be sub-contracted to shore workshops with confirmed marine experience, or done on board by visiting fabricators. Either way, the same supervision and certification chain applies.
After the work
The end of welding work is not the end of the procedure. Fire watch continues for a defined post-work period - typically 30-60 minutes - because hot metal can ignite delayed combustibles. The work is logged, the permit is closed off, and any class-relevant work is presented for inspection at the next available survey.
This procedural completeness is what separates routine maintenance welding from the next casualty report.
For welding consumables, gas supply, and marine engineering coordination at Chennai Port, see our ship chandler at Chennai Port engineering scope.