wenzhou domos fluid equipment co.,ltd

Quality Control

Our inspection plan is beginning with the designing drawings.

 Gate valve

Design & Manufacture conform to API 600/ASME B16.34

Face to Face confirm to customer’s requirements.

Flange dimension conforms to ASME B16.47-A

Test & Inspect  conform to API 598

 With these standard ,we design the mould drawings and make the mould.Valve are got from the mould so that all the designing details could be trackable.

Our inspection items are as follows.

Materials test;visual inspection,dimension check,,skilled machining inspection,assembly /perfomance test;pressure test;final inspection,NDE if required.

 First we purchase castings,wedge,stem,sealing materials,gasket,spring ,bolts&nuts,welding materials and so on.

When the castings and parts arrive,we check the quality report first and check if it is according to order.And the materials should be confirmed to the respective  materials specifications.

After that we visual inspect the castings&parts.The character on the body should be right&clear.the castings surfaceand internals have no sand holes,burrs,scale,cracks and so on according to MSS SP55.

For the nominal size,pressure,materials ,heating No.and other necessary should be shown on the valve body.

The bore have no any defect.And the body,bonnet,stem,sealing parts should be no any defect by visual.

And then dimension check.At the same time,the thickness should be checked.

The dimenson should be checked according to the drawings.

During the process,we have 3 times inspection including first inspection,middle inspection &finished inspection.After rough machining,we have to do visual inspection&dimension checking first .If it is ok,then we shotblast and polishing the body.And do dimension inspection&record it.If it is ok and then we do skilled machining ,do dimension inspection &record it.And then shotblast for the second time.And machine the weldings of disc .For the machined parts,we have to measure the size and adjust the disc.All the parts size should be according to the drawings.

Before assembling,the parts should be clean and dry.And visual inspection the parts.check the connection dimension.The assembly should be according to the respective specifications.Finishing assembling,the gate valve in order have to be open and closed for several times to check if it is in good function.

For pressure test,it is include shell test,high pressure test,&gas pressure test according to API598. 

Each valve will be pressure tested by inspectors according to relevant testing standards. The pressure testing mainly include: intensity test, back seat test, hydraulic test and pneumatic sealing test. The testing method of different valve type varies according to relevant standards.

The testing process of each valve will be recorded, the main thing being recorded are: serial number, size, type, material, heat number of pressure containing parts, testing pressure, duration of pressure held and the testing result.The gate valve in order will be arranged for high pressure test.It will be marked.

Final inspection include painting inspection ,visual inspection for finished gate valve ,final sizing dimensions&packing inspection..

To be sure the painting colour is according to customer's requirements and the thickness is satisfied with customer.And no any destroy for paintings.

The length&the flange face should be final inspected.

Check name plate and marks are in correct way.

Collect the heating No. and make the quality certificates.

Packing inspection:Package type is steel frame.We will welded the steel frame for a suitable package of gate valve for that heavy valve.

We will make plastic paper outside the steel frame to provent it from water.

The shipping marks should be according to customer's requirements.

If other inspection requires,we have to according to the customers requirements.