An eccentrically mounted rotor spins inside a casing partly filled with seal liquid, usually water, which is thrown outward into a ring that alternately expands and compresses the spaces between the rotor blades. Gas is drawn in through the inlet port on the expanding side and pushed out the discharge port on the compressing side, with the liquid ring acting as the piston and the only moving part being the rotor. That simplicity is why these pumps run for decades, and why most failures come down to a short list of causes: worn cones or rotors, corrosion, cavitation, seal water problems and bearing failure.

Teardown and failure analysis. Every pump is completely disassembled and every component measured against OEM specifications. We identify the cause of the failure, not just the failed part, so the rebuilt pump does not come back with the same problem.

Cast iron repair. Cast iron repair is considered by many to be a lost art. Precise Mechanical performs these operations on a daily basis. Cracked heads, eroded bodies and corroded cones are welded, machined and returned to spec rather than scrapped.

Stainless steel clad repairs. Worn or corroded cast iron cones, heads, port plates and bodies are clad in 304L or 316L stainless steel, machined to original dimensions, and returned to service with better corrosion resistance than the original casting. All cladding is done in-house.

Rotor and shaft work. Rotors are repaired, rebalanced, or remanufactured. Shafts are straightened, sleeved, or made new. Our 400-ton horizontal press handles rotor-to-shaft assembly on the largest pumps, and lathes up to 240 inches between centers handle the longest shafts.

Remanufactured and reverse-engineered parts. Parts that are no longer available from the manufacturer are reverse engineered from the original and machined in our shop. All materials and remanufactured parts meet current OEM specifications.

Assembly, coating and final inspection. Every clearance is double-checked during assembly. The pump is primed and painted to your specification and inspected before it is crated.

A rebuild is the right time to fix what caused the failure. Common upgrades:

• Stainless steel cladding of cast iron cones, heads and bodies (304L or 316L) for corrosive seal water or process gas.
• Protective coatings on internal surfaces to slow erosion and scale buildup.
• Seal water recirculation systems with heat exchanger, flow monitor and controls to stabilize seal water temperature and cut fresh water consumption.
• Material upgrades on rotors, shafts and port plates where the original material was the weak link.
• Packaging with a new motor, VFD, gearbox or belt drive and manifold.

Packaged units

When the rebuild timeline is longer than the outage, there are two alternatives. Our exchange program keeps rebuilt pumps in stock for the AT, CL, SC, H/L, 904 and XL series and Somarakis SV series; we ship the exchange pump and take your core back. For pumps that are too far gone or obsolete, we manufacture drop-in replacements for Nash CL, 2BE, AT, SC, 904 and HC series and the PM 5986 line for Somarakis SV and HV series.

Exchange program · Rebuild vs. replace vs. exchange