Marine boilers are essential pieces of equipment on ships and other watercraft. They provide a source of heat for various purposes, such as powering the engines, heating cabins and other areas, and keeping the vessel warm in cold weather. However, marine boilers can also be a source of problems if they’re not properly maintained.
In this article, we’ll take a look at some of the most common problems with marine boilers and how to solve them.
Leaky Manhole Joint
One of the most common problems with marine boilers is a leaky manhole joint. These leaks can be very difficult to find and repair, but they are one of the most common causes of boiler problems. If there is a suspected leaky manhole joint, it is important to take care of it as soon as possible to prevent further damage to the boiler.
There are a few different ways to repair a leaky manhole joint, but the most common method is to:
- Maintain a spigot clearance of at least 1.5 millimeters, in order to position the door centrally for even gasket loading.
- Use a new gasket every time.
- Avoid putting too much strain on the door studs, which may stretch.
- Pull-up studs can be re-tightened after steam has risen or the nut has warmed up.
- To avoid damaging the door, use a rope to gently lower or remove it.
- Mark the dogs and nuts so they can be put back in the same door.
- Examine the studs and nuts for signs of wear.
- Before reassembling, carefully inspect the matting/landing surface for erosion and corrosion on the door and boiler.
Repairs In Damaged Smoke Tube Boilers
Smoke tube damage is one of the most common problems with marine boilers. This can be caused by a variety of factors, including corrosion, poor maintenance, or simply wear and tear. Smoke tube damage can lead to a loss of boiler efficiency, and in extreme cases, boiler failure.
There are a few ways to solve this problem:
- Hydrostatic testing to identify the leaking tubes.
- Clear the tube plate by cutting the tubes on one end. The tube collapsed inside the tube plate on the other end.
- Take the tube out of the collapsed end.
- Weld a short tube to the tube plate.
- Wrap the spare tapered plugs around the stud ends of the tube plates.
- Tack weld the tube plugs into place.
- Alternatively, a long steel bar that is bolted and threaded at both ends can be used to hold the plugs in place.
- A hydrostatic pressure test is performed to ensure that there are no leaks.
- Under full steam pressure, flush the boiler and inspect the plugs for leaks.
Temporary Repair Procedure for Smoke Tube Leakage
- Allow the boiler to cool before removing the soot.
- Allow the boiler to depressurise before opening the blow down valve for draining.
- Cut a hole in the side of the relevant smoke tube after entering the boiler flue box.
- With a wire brush, clean the rim of the smoke tube.
- Make a circular plate (15 millimetres thick) whose diameter is the same as the smoke tube and grind the top edge to 30 degrees.
- Weld the plate into place at the top of the smoke tube as shown.
- Enter the boiler furnace and make a similar hole in the relevant smoke tube’s end.
- Steps 4–6 should be repeated for the lower plate.
- Before starting the boiler, refill it and check for leaks.
- When the boiler is pressurised, start it up and check for leaks.
Please keep in mind that any temporary repairs to smoke tubes or boiler tubes should be followed up on as soon as possible.
Plugging of Water Marine Boilers’ Tubes
Plugging can occur due to a variety of reasons, including poor water quality, low boiler water alkalinity, and high dissolved solids content. Additionally, economizer tubes can become plugged with scale or other deposits.
Plugging of economizer tubes can lead to decreased water boiler efficiency and increased fuel costs.
There are a few ways to solve this problem:
- Steam pressure must be removed and the oil burner dismantled in the event of tube failure.
- If the leak can be seen through the burner hole, the boiler can be emptied and repairs can begin.
- Otherwise, the feed pump provides pressure to the boiler. Water flow will indicate the location of the leak.
- From the burner hole, this flow may be invisible. Remove the inspection door and enter the furnace if it’s not visible. Enter the generating tube section if the tube failure is still not found.
- The bottom of the generating tubes and membrane walls can be inspected for leakage from this location.
- If the leakage was caused by the membrane walls or the generating tube, remove the inspection door at the smoke connection pipe, then identify the generating tube/ membrane tube where the failure occurred.
- Economizers may also cause leakage.
- It is possible to determine which uptake has caused the leakage by removing the inspection door at the bottom of the economiser.
- Other inspection doors should be removed as needed to highlight the damage register.
- After removing a damaged convection register or tube, and repairing/ plugging the remaining tube studs, a new tube or register should be installed as soon as possible.
- Longer periods of operation with one or more registers missing pose a risk of further boiler damage due to increased heat leads on the parts adjacent to the ones removed.
One of the most important pieces of equipment on a ship is the boiler. Marine Boilers are used to create steam, which powers the ship’s engines. Without a properly functioning boiler, a ship can’t move. That’s why it’s so important to keep an eye out for common problems that can occur with marine boilers. By being aware of these problems, you can take steps to prevent them or fix them before they cause major damage.
