Irwin Marine Services — Keeping our customers out of the dockyard is always our primary objective and an improperly repaired overboard pipe (ship repair) has the potential to land a vessel in the dockyard.
The advantages of working with Irwin Marine Services include:
- A large portfolio of ABS approved welding procedures and ABS qualified experienced welders
- Stock on hand of raw pipe, flanges and various grades and thicknesses of ship building steel
- A strong culture of quality and safety
- English speaking staff are available 24 hours
In this case, we had a DIN400 (16”) overboard pipe with a leak outboard of the overboard valve. Fortunately, after discharge and trimming, the overboard pipe was above the waterline so no divers were required.
- Ultrasonically test the damaged pipe to determine the length to be cropped and to ensure sound metal for welding in the new flange.
- Fabricate a new coated spool piece
- Cut out the damaged pipe below the overboard valve and weld in a new flange
- NDT as required by the classification society
- Apply a two-part epoxy coating in areas damaged by welding and cutting.
- Fit the new coated spool piece
- Operational pressure test
Before the job, we were asked by the technical management why we wanted to weld in a new flange and insert a spool piece rather than welding in a new pipe section via a butt weld. We explained that when you cut a damaged pipe, even after doing a UT thickness test, you never really know what it will look like inside. For a full penetration butt weld on a pipe, you either put a backing ring(like a chill ring) on the inside of the pipe and then do a one side weld from the outside or you weld from the outside, gouge the inner weld to sound metal on the inside and then weld again on the inside. Since the old pipe may be pitted, it might not be possible to properly seat the backing ring. Regarding welding from both sides, while technically possible to ask a welder to bend over and stick his head inside a 400mm (16”) pipe, this is not something you want to do if there is a better method.
Another advantage of fitting a new coated spool piece, is the spool piece can be properly rotationally lined with polyethylene (PE) in our workshop before the repair. A workshop coating is always superior to a locally applied epoxy coating and a pipe rotationally lined by Irwin Rotational Lining will generally still be in great shape for the life of the vessel.
Irwin Marine Services should be your first choice for ship repair in China.