Revisiting on-site pressure testing of valves”

On-site pressure testing is absolutely necessary; not all valves leave the factory as being qualified. Pressure testing is indeed essential, but I think the current testing equipment is too basic and relies too much on manual operation – improvements should be made in this area! ! !

The quality of valves varies, so pressure testing is necessary, especially for those used in process pipelines, as hazardous chemicals are flammable, explosive, and toxic. Safety comes first at all times.

This post was last edited by lxzzl on 2010-4-27 09:01. Advanced international standards such as API, DIN, and JIS do not require a second pressure test on site; then why do China’s standards require it? I personally speculate that this may be due to the lower processing capabilities and quality control standards of the valve manufacturers, as well as the fact that these manufacturers might not carry out pressure testing. Currently, the quality systems of most valve manufacturers are continuously being improved, which allows for effective assurance of valve quality. Under such circumstances, why remain unchanged?

Valves must undergo pressure testing on-site. On the one hand, this is required by relevant standards, as well as to ensure safe operation of pressure pipelines once they are put into use. On the other hand, although many manufacturers provide valves with certificates of conformity and inspection records, during the on-site inspections of the projects I have been involved in (around 20 projects in total), a certain number of valves still failed to meet the requirements in terms of strength and tightness. Therefore, it is essential to conduct on-site testing of valves in order to reduce potential risks during installation, commissioning, and operation.

Based on experience, quite a number of problems were identified during field tests. Given the national conditions, testing is still necessary at present. This is because some manufacturers reduce quality control in order to cut costs

This post was last edited by lxzzl on 2010-4-27 09:06. There are several aspects to valve pressure testing: one is strength testing, another is tightness testing, and there is also sealing performance testing. Pressure testing of pipelines can reveal some issues related to the quality of valves, but it cannot expose all of them. For example, to determine whether a valve is leaking internally, there are a dozen or so valves in one pipeline, all connected in series – how can you figure out which valve might be leaking? It’s impossible to know. Construction companies are usually concerned with whether the entire pipeline system is compliant or not, and not whether individual valves are compliant or not. However, from the owner’s perspective, if a valve leaks internally, the situation can be very serious. It will be too late to deal with it by then. The construction unit represents the final link in the project’s implementation process. If this final step isn’t properly handled, and the problem is only discovered after the project is put into operation, things will get very bad! Care makes for a long-lasting ship! For important material pipelines, it is best to conduct a 100% pressure test.

Given the national situation, what was said above makes sense; it’s best to analyze each case on its own. For projects, for valves that are not located in critical areas, it’s better to avoid testing them if possible. Try to gain the owner’s understanding; if the owner is unaware of this, we should pretend we’re not aware as well. For valves in critical areas, especially those on pipelines handling hazardous materials, it is advisable to conduct tests in line with safety principles.

This is our requirement: for all valves purchased by the management company, the valve manufacturers assign quality control personnel who carry out pressure testing on each valve in accordance with API598. Valves that pass the pressure testing are issued with an approval tag made of aluminum before leaving the factory, and the relevant personnel also sign the quality certification documents; upon arrival at the site, 5% of the valves are selected for pressure testing according to the specifications

In favor of pressure testing; it’s supported for safety reasons!

Someone once said that a valve that passes the pressure test is qualified, even if it’s made of paper! I wonder if anyone has heard of such an absurd theory! Pressure testing is merely a inspection method; it can be carried out on a sample basis, but it’s still best to conduct pressure testing on critical areas!

I think valves in critical areas should be tested first before installation. We replaced a shut-off valve in a chlorine pipeline; right after the replacement, the valve body started leaking when a pressure of 0.2 MPa was applied. It was really disgusting, so we drained the pipeline and got a new one from the warehouse to try it out, but it leaked even more severely than the previous one. There were big red marks indicating that those valves were qualified... I am in favor of conducting pressure tests on-site, because even after everything is installed, it’s not guaranteed that every bolt is properly secured. The connection points are weak points, and a considerable number of stainless steel bolts have issues...

Which standard requires that valves must be pressure-tested on-site?

Reply to 1# zxz017: 1. On-site pressure testing is very necessary, especially for important material pipelines, in order to avoid various potential problems that may arise during transportation and commissioning. 2. The valve installation quota of the construction unit includes the cost for valve pressure testing.

It is extremely necessary during the on-site pressure testing of valves； Resolutely support 100% on-site pressure testing of valves. 1. The products delivered by valve manufacturers cannot be guaranteed to be in exactly the same condition as when they were produced, even after long-distance transportation. 2. Even with good transportation protection, it is not possible to guarantee 100% compliance of the products upon arrival; nor can on-site testing ensure 100% compliance. Nevertheless, it still helps to effectively reduce the flow of defective products into construction sites. 3. Foreign-made valves are not tested on-site; perhaps it’s because they don’t trust Chinese technology, rather than there being no need for such testing. If there were no need, then testing on-site wouldn’t be necessary. Based on years of experience, it has been found that many foreign-made valves leak after being put into use. 4. Online pressure testing of pipelines cannot fully detect issues such as valve leakage or sealing problems, including internal leaks. 5. Doing this can effectively reduce the occurrence of marginal costs.

Is it still necessary to perform on-site pressure testing after the pneumatic control valve arrives? On-off valves and control valves

Pressure testing must be carried out on-site; mainly because the quality control of many valves these days is concerning, and it’s really worrying not to conduct pressure testing on-site.

If, during on-site pressure testing of valves, you find that several, a dozen, dozens, or even all valves from the same batch manufactured by the same manufacturer are leaking, then it becomes clear why such testing is necessary. On-site pressure testing of valves is the final inspection step before pressure-bearing components in pipelines are put into use; it is crucial for ensuring smooth operation and long-term safety, and it cannot be taken lightly or based on experience alone. At the same time, manufacturers are required to fulfill their contractual obligations by conducting pressure tests prior to shipment, and to earnestly uphold their responsibilities for ensuring product quality.