Describe common failures of Sulzer engines.
18 Jun '17, 10:15
Below are known failures from our experience:
Diesel Generator Engines:
Wartsila Vasa Generators – Unit exhaust valve dislodged and fell in combustion space damaged several components and turbocharger. The complete generator was overhauled.
A) F.O. High Pressure Pipes
- 1) High Pressure Pipes fracture
- 2) Landing sealing damage: It is happening due to repeated use and excessive tightening. Material needs to be made tougher
- 3) H.P. pipe between clamp and metallic pipe abrasion wear found to be prominent leading to thinning down of metal and failure of material. No packing material is provided between the two metals contacts to avoid abrasion due to vibration.
- 4) Alignment of high pressure pipes is difficult. As the threads are of very fine type and there is no room for minor adjustments in this type of rigid pipes, it takes lots of skill and effort to align properly. Most of the time it leads to thread damage, wrong threading, long delays, continuous leakages found on the cylinder head area and fire hazard.
B) Piston Ring Breakage
- 1) Due to thermal stresses (Low ambient temperatures): This happens when piston rings especially the top ring is subjected to combustion temperature and the cold scavenging air alternately for prolonged periods of time.
C) Piston crown and skirt damage.
- 1) This happens when slapping of the skirt takes place. The rubbing band gets worn out fast and this leads to skirt slapping.
D) Liner Cracks:
- 1) Due to top piston ring breakage, causes blow-by, piston ring sticking and thermal cracks.
E) Liner Scuffing:
- 1) Ridges are formed on liner surface causing deep steps at a location of top piston ring at TDC position.
- 2) Instantaneous micro seizure of piston rings, making and breaking of these welds with liner material causes abrasive metal abrasive wearing away the liner material.
F) Cylinder cover bolts breakage:
- 1) Cylinder cover bolt found broken with no apparent reasons. The ultrasonic test was done and found all the bolts are good. May be an isolated case, however, reasons for such failures are very serious.
G) Cylinder Head cracks:
- 1) Around the mounting pockets of air start valve, fuel injection valve and indicator valve
H) Fuel Pump Body cracks:
- 1) Fuel pump blocks developed hairline cracks .Fuel pump cracked blocks renewed with new spare block. The other pump units were analyzed for cracks and found some are appearing small hail line cracks in the body. Suggested additional tightening of 80KN-m proved no result. Replaced with new pump blocks and cracked blocks landed for analysis.
I) Plunger and Barrel wearing/ Seizure or sticking
- 1) Material should be able to withstand a certain amount of catalytic fines carry over even after purification
J) Exhaust valve burn out before time.
18 Jun '17, 10:43