The oil supply pump mechanical seal keeps breaking down
Thread Content
Our factory has one oil supply pump, a multi-stage centrifugal pump. Transport medium: No. 0 light diesel. The pressure is less than 4 Mpa, and the flow rate is in the range of over 10 liters. Due to excessive current, it was returned to the manufacturer for repair; components such as the impeller, shaft sleeve, bearings, and mechanical seal were replaced, and a dynamic balance test was conducted at the equipment manufacturer with satisfactory results. After returning and reinstalling, the trial run went very well. But a few days later, when the pump was started again, a ‘bang’ sound was heard and there was a leak at the mechanical seal. Upon removal and inspection, it was found that the back side of the static ring (soft material) of the mechanical seal was fractured; the sealing surface was intact, while the dynamic ring of the mechanical seal was made of cemented carbide. A few days after replacing the mechanical seal, the same issue occurred again during one pump start-up. The damaged area is also the back side of the stationary ring. Please help analyze the reasons
Check the dynamic balance data sheet (1. Is the standard G1.0 or G2.5?)； 2. Check whether the speed used in the dynamic balance calculation is the operating speed ； Check whether the exhaust gas is completely cleared before starting
Based on an analysis of the described phenomenon, it seems that the static ring experiences axial displacement during operation. Retaining ring, balance, negative pressure?
Try switching to a screw pump; the situation will stabilize.
Was the machine rotated before starting? Why do I feel it’s caused by the adhesion of the sealing surfaces?
It works properly after installation. Could it be a problem with the material of the static ring, which isn’t resistant to diesel? What material is the static ring made of?
Could it be that the mechanical seal wasn’t installed correctly? Is it possible that the spring is too tight, resulting in excessive pressure on the end faces and causing cracks in the anti-rotation pin area of the stationary ring?