Houston Hydrostatic Testing to API 598 and 6D Standards

Houston Hydrostatic Valve Testing

Hydrostatic Testing is a testing process used to test components like valves, gas cylinders, and piping in the plumbing system for leaks and strength. By plumbing services may use the method, it’s also used in other industries. Usually, hydro tests are needed after repairs and shutdowns to ensure that the equipment is operating optimally under the desired conditions.

Hydrostatic Testing can’t be performed when the equipment is working or normally operating. It can’t efficiently monitor equipment for potential leaks after the test(s) have been run. Generally, on-steam equipment integrity needs to be managed by a fixed equipment mechanical integrity system that’s put in place with specific guidelines.

Even though hydrostatic Testing is a nondestructive method of leak detection, some equipment depending on its condition can rupture and consequently fail if the inspection exceeds the test pressure or if there is a small crack that then propagates during the test.

How Does Pressure Testing Houston Work?

Generally, hydrostatic Testing works by filling the component entirely with water, then removing air in the unit, and pressurizing the system, usually up to 1.5 times the pressure limit of a unit. The pressure is held for a set amount of time, giving the tester enough time to inspect the system for potential leaks or cracks.

In many industries, a visual inspection will need to be enhanced using fluorescent dyes or a liquid to determine where the cracks or leaks originate.

Hydrostatic Pressure Testing Valves – Common Methods


Hydrostatic Testing is one of the more common types of pressure testing, but three very common techniques are used. These techniques are used to test pressure in cylinders and vessels.


Hydrostatic Test Using The Water Jacket Method

Hydrostatic testing Houston is a method that works by filling the vessel with water and then loading into a sealed chamber referred to as a test jacket. The vessel is pressurized inside the jacket for a given amount of time. This will mean that the vessel expands in the test jacket, resulting in the water being forced into the glass tube, which is then used to measure the total expansion.

After the expansion is recorded, the jacket is depressurized, which shrinks to its original size. The water will then flow back into the test jacket.

There are times when the vessel will not return to its original size. This is referred to as permanent expansion. The difference between both sizes (permanent expansion and total expansion) helps determine if they are fit for service. Usually, the higher the expansion ratio, the higher the chance that the vessel in question will have to be decommissioned.

The Direct Expansion Method

The method involves filling your vessel or a cylinder with a given amount of water and then pressurizing the system. Then some amount of water is expelled from the system after the pressure is normalized. The total and permanent expansion figures are determined by recording how much water was pushed into the test vessel, the pressure and how much water was expelled.

Proof Pressure Method

The proof pressure test works by applying internal pressure to determine if the vessel has leaks or maybe any other weakness like a thinner wall that could rupture. In the US, this method is used when permanent and total expansion values don’t need to be recorded.

Alternative Methods

There is some equipment that’s not designed to handle the load of a pressure test to see if a leak present. An alternative method like pneumatic Testing can be used in situations like these. Pneumatic Testing is another type of pressure test which mainly works by pressurizing the vessel with gas like nitrogen. However, special caution needs to be observed since gaseous mediums can be compressed and contained in much larger amounts as compared to if hydrostatic (water) testing.


Valves Tested to API 598 & 6D Standards

Generally, specifications like API598 are mainly for leakage of soft seated valves, which call for having ‘0’ air bubbles and drops of water under a specific test condition over a set period of time. The valves are referred to as ‘zero leakage’ valves. Though there is no such thing as a zero leakage valve since there are always going to be microscopic leaks of material that cross the seat or the packing boundaries, especially when it’s gases like hydrogen and other similar gas molecules. The other common term used for this is bubble tight.

The leakage performance of a soft seated valve may also be called a Class VI, having the tightest leakage under FCI 70-2, and applies to resilient seated control valves. Though FCI 70-2 may allow for a few air bubbles per minute to escape, with increases with the size of the valve, where was with API598 and MSS SP-61, they don’t.

In actuality, even a metal seat valve, the API598 acceptance for leaks may allow for fewer leaks compared to FCI 70-2 and 50NB. Though if zero leakage metal seated valves are considered, then API 6D and API 598, zero leakage measures can be stated.

There may also be special provisions for mainly zero leakage gate valves to ISO 5208 and BS 6755. Metal seated valves like ball valves and butterfly valves have an acceptable leakage level during Testing, which is defined as the amount of liquid seen under test conditions and also over the period of the test.

We Use The Best and Latest Valve Pressure Testing Machine

Our team uses the best and latest valve pressure testing machines to ensure the most accurate readings. In addition, we also use isolation testing and camera inspection to ensure accuracy especially depending on what’s being tested. However, businesses and engineers can contact us to find out what machines our team will use to test their specific valves.