Research On Key Technology Of The Chemical Process Pump Casing Parts Production

The chemical process pumps are important components for the chemical industrial production, its quality relates the stable operation and safety of the entire production line, and therefore they are required very highly strict requirements for quality control. The chemical process pumps are mainly made of casing, cover, impellers etc. and most parts casted by investment casting or sand casting then processed final machined. The production processes are complex and last long periods, it brings a great challenge to the production quality control and improvements.Distinguished the conventional process way, produce the productions and inspect for them, this paper present an approach that apply the quality management system tools to systemic control and improve the quality at all stage, from the beginning of the projects to its end. The quality tools include the advanced product quality planning(APQP) and production parts approval process(PPAP) etc. This approach controlled good quality.Be aim to the casting shrinkage defects of the production for the WCB carbon steel P type casing, analyzed the defects all possible factors. They are caused because of the inadequacy of the casing casting technics which easily lead to casting defects; meanwhile there are also existing process loopholes that missed inspection and monitoring for the welding repaired casting defective parts. The improper casting technics parameters is main reason which leading to the plenty of casting shrinkage defects. Based on the analysis, applied the Pro CAST simulating the casting process and found the previous casting technics would easily cause the casting defects, using the orthogonal test for optimization the casting process parameters of the casing and final obtained the optimization casting parameters: the pouring temperature is 1510℃, the shell preheat temperature is 850℃、the shell casting full time is 15 s.Meanwhile, improved the welding repair process of the productions and inspections plan, and added the control actions for welding repair parts. After all above actions done, the casting quality has been improved, the microstructure, compositions distributions, mechanical properties etc. for later production(CF8 and WCB) all fulfill the requirements, the parts inspection results are all acceptable including the radiographic testing, hydraulic pressure testing, penetrate testing, and meet the quality requirements. The acceptable ratio enhanced from 50% to 100%, the internal defective risk greatly decreased.For the massive machining quality issue of the S type casing productions, by fish bone analyzed the most possible variation factors may cause the dimensions unacceptable, then step by step analyzed and excluded the factors as below, the capacity of the equipment, testing methods, the impact of stress on the product, hydraulic testing impact, etc., finally found the main cause is the hydraulic testing will distort the casing dimensions, meanwhile there are great flaws on manufacturing process flow, control plan and inspections. Base on above analysis therefore raised the corresponding corrective and preventive actions, carry out the hydraulic test by manual instead of automotive operations, changed the process flow, improved the control plans and inspection plans, and improved the workshop operations and the flange machined surface protections. After above improvement actions, the acceptable ratio raised greatly from the previous less than 70% to 98% around. It provided an important guarantee for the stable mass production of S type casing.The research fully indicated that it’s a must to carefully consider and confirm on the advanced product quality planning at the early stage of the production development, focus on the critical quality control points of the product during all stages, which including the request for quotation, production preparation, purchase order confirmation and management, mid-review, production delivery, therefore it would high efficient and economical to ensure the projects run smoothly and the improve the productions quality.