Key Notes on Dalian Chemical Pump Pipeline Connection

Pipeline Connection Guidelines for Dalian Chemical Pumps

As a major domestic chemical equipment manufacturing base, Dalian’s chemical pumps (horizontal centrifugal & anti-corrosion pumps from Dalian Da Nai Pump) serve harsh corrosive, medium-high pressure and frigid northern environments. Proper piping connection determines pump efficiency, service life and safety, with key considerations as follows:

1. Stress Control & Layout of Suction/Discharge Pipes

Most Dalian chemical pumps are horizontal, highly susceptible to axial and radial piping stress from pipe weight and thermal expansion, which may cause shaft distortion, seal leakage or pump rupture.

- Independent pipe supports are mandatory; no pipe loads on pump casings.

- Suction lines: short, large-diameter and straight, one to two sizes bigger than pump inlet, with bottom eccentric reducers to eliminate air accumulation and cavitation common in cold northern winters.

- Discharge lines: install flexible joints or expansion joints to absorb thermal deformation (temperature swing over 30℃ in Dalian), preventing vibration and stress transfer to pumps.

 2. Precise Connection of Sealing Auxiliary Piping

Most pumps come with cartridge mechanical seals with strict auxiliary circuit requirements:

- Flush piping: flush liquid pressure 0.05–0.1 MPa higher than pump cavity, filtered through ≥50μm strainers to avoid seal surface abrasion.

- Cooling circuits for high-temperature media: equipped with electric heat tracing to prevent freezing below -10℃ in Dalian winters; pipe slope ≥0.5‰ to drain residual water.

- Packing seal water injection lines must stay unobstructed to avoid medium leakage.

 3. Material Matching & Anti-Corrosion Sealing

Wetted parts adopt 316L stainless steel, duplex steel or fluorine lining. Flanges, gaskets and valves shall match pump materials:

- Smooth flange sealing faces, medium-compatible spiral wound gaskets; asbestos gaskets are prohibited due to corrosion risks.

- Eliminate stagnant dead zones to prevent medium crystallization and clogging; smooth pipe transitions without blind tees. Purge welding slag and debris via compressed air or water before commissioning.

 4. Pre-Commissioning Safety Inspection

- Fully vent air via high-point air release valves to avoid air binding on startup.

- Preheat pipes in winter to prevent cracking from low temperature.

- Standard valve operation: close discharge valve and fully open suction valve during startup, then gradually open discharge valve to avoid abrupt flow vibration.

 Conclusion

Combining northern low-temperature conditions and anti-corrosion pump characteristics, standardized piping work covering stress control, sealing circuits, material compatibility and pre-commissioning inspection minimizes failures and ensures safe chemical operation.