MVI Quality Control Procedure

1. References
MSS SP 55: Quality Standard for Steel Castings for Valves, Flanges, Fittings and Other Piping Components. Visual Method for Evaluation of Surface Irregularities
API 598 Valve Inspection and Testing
This mark means should take pictures for evidence.

 
2. Objective
This procedure is to assure goods qualified according to international standard, promoting our service and making client satisfied with our goods.
 
3. Raw material quality

3.1 It is not acceptable if casting surface with gas porosity, cracks, macro shrinkage, sand inclusions, laps, cold shuts etc. Cutting marks shall be smooth. Casted hole cannot be wasted hole or blind hole, any folds and veining not allowed. Measuring thickness and machining allowance is ok or not. The casted marking as size, pressure, material, heat no. shall be clear visually.

3.2 Forging surface is not allowed with crack, folds, cavities etc. defects. If any tortuosity or distortion, it shall be within 1mm. Machining allowance shall be measured if it is enough. Forged marking as size, pressure, material and heat no. must be clear visually.

3.3 For other parts surface, any rusting, damage, burr, scratch etc. fault is prohibited.
3.4 Surface with nitriding, ENP, or chemical treatment must be well-distributed and nice color.
3.5 For those surface treatment which specifies thickness, shall review and check the documents sub-vendor supplied.
3.6 Inspector shall check carefully the raw material mill certificate that supplier submitted.
 
4.Machining Process Inspection

4.1 Supplier is required to do the first inspection for coming raw material, to avoid unqualified materials in a batch making delivery delayed. Inspector shall review and check the supplier's inspection report carefully. If supplier can't submit the inspection report, our inspector shall do the inspection on supplier's coming material and records accordingly.

4.2 Machining routing inspection scope includes dimension, visual appearance, marking and quantity examination, and all of these shall be recorded.
4.2 Machining process inspection: our inspector chooses the objective parts at random which has been inspected by the supplier themselves and exam to assure the products quality. Our company specifies DN50 and above size valves in alloy steel, SS, special material etc. shall be inspected in full quantity. For other normal material valve, choose randomly and do inspection as per below quantity:

Remark:
1. A lot shall be accepted if all the samples of the lot meet the specified acceptance criteria.
2.If there is one sample failed in the random inspection, inspector shall do examination on all of balance quantity.
 
5.Assembly Inspection

5.1Before the assembly of first valve, our inspector shall check the part material if comply with order specification according to drawing. It includes dimension, material, marking etc. After ready, supplier assembles first valve and finish pressure test accordingly. Only after the first valve is tested and qualified, then do assembly for the balance.

5.2 Inspection during assembly process is also required. Inspector shall check the part material correct or not, and visually inspect appearance of assembled valve, for example, if bolts/nuts between body connectors of ball valve are in the same level, if the height of bare shaft in gate valve is complied with standard etc.

5.3 After operator/actuator installation on valve, factory shall do commissioning to assure the valve on-off function. If painting is required, its surface shall be smooth and with clear on-off marking (Chinese words is prohibited). If the valve is with lever, it shall be operated smoothly.
 
6. Pressure test

6.1 Supplier shall do pressure test for each valve. To be more effectively, our inspector can witness the test process when supplier test for the first time, if it is available. For these valves succeeded in first test, inspector shall record avoiding repeat inspection.
6.2 For those qualified in pressure test without our witness, inspector shall do testing again at certain quantity. For each inspection lot, samples shall be taken in accordance with below table:

Remark:
1. A lot shall be accepted if all the samples of the lot meet the specified acceptance criteria.
2. If any of the samples fails to meet the acceptance criteria, additional samples equal to the original number shall be inspected. If these samples meet the acceptance criteria, the lot shall be accepted with the exception of the initially rejected items. If any of the additionally inspected samples fails to meet the acceptance criteria, then 100% of the lot shall be inspected or, at the purchaser's discretion, the entire lot shall be rejected.
 
7. Surface treatment and painting

7.1 During valve manufacture, supplier is required to protect the valve surface very well, especially flange ends, flange sealing face, inner passage edge, lining etc.
7.2 Before painting, inspector shall check and mare sure each valve is clean, dry and smooth surface.

7.3 Primer painting shall be spraying or coating. After drying, the surface shall be grinded smoothly with sand paper.
7.4 Top painting must be done by spray or stove varnish. Inspector shall check the finished surface if there is any slipping, peeling, wrinkle, bubbles or craters etc.
 
8. Packing

8.1 Before packed, inspector shall check if each valve has been with nameplate or tag, if the nameplate is marked in accordance with order specification.
8.2 Valve inner passage shall be clean. Valve body ends shall be covered with close fitting protectors (e.g. plastic caps) to protect the machined parts. Valves shall be delivered in the close position.

8.3 Prior to be packed in the box, valves shall be put in plastic bag or twined with film to protect ingress of dirt and moisture.

8.4 Valves shall be packed in plywood case or wooden case. If wooden case, fumigation certificate shall be submitted.
8.5 After packing, inspector shall check and make sure the packed valve quantity is in line with packing list, and each valve has been secured well.
8.6 Prior case sealed, desiccant shall be put into the cases and any documents if client requires.

8.7 After case sealed, supplier shall bale the case with 3 steel wires at least to secure further.
8.8 At last, put shipping mark and quarantine inspection batch number on both sides of case.