Half an hour of intense fire is something you hope a valve never faces. Especially if the medium running through that valve is oil or gas.
But 30 minutes of direct contact with flames reaching temperatures as high as 980°C is exactly what Master Flo fire safe chokes must go through to receive the API 6FA certification that necessitates such testing.
A Master Flo fire safe choke undergoes testing at the third-party test laboratory.
“Depending on the application, there is a requirement for increased safety in shut-off devices such as ESDs, gate valves and other shut-off devices,” explains Master Flo Engineering Manager Peter Brzezicki. “This led to API 6FA fire safe requirements for these devices. In case there’s a fire, the valve can shut down and isolate the flow, preventing flammable fluids from spreading.”
Even though choke valves are not isolation devices, as Brzezicki points out, certain customers began demanding this feature, leading to Master Flo having conducted over 29 different API 6FA tests at a third-party test laboratory.
“We still conduct a few a year, hopefully less and less as we build up our portfolio, as once you have qualified a configuration, the API 6FA specification applies a scaling system that encompasses various sizes and pressures,” said Brzezicki.
Should the body or seal material change though, that would typically require a new test.
During the test, the valve is under pressure as water is pumped through it. Then the flames are unleashed on the body and bonnet, with the integrity of the seals being put under the highest amount of scrutiny to make sure they are not leaking beyond an allowable amount.
Of the 29 tests Master Flo has subjected their chokes to, only two have ever failed, requiring a redesign of the fire shield in order to obtain the certificates for those choke configurations.
“The main two problems fire can cause to a valve is 1) it can melt your seals and 2) is your metal pressure containing components such as bolting and bonnets heating up,” outlines Brzezicki. “If your seals melt and deform, then the valve will leak, and if your bolting heats up, it will get a little bit weaker and may stretch. If your bolting stretches or your bonnet expands too much, then you might get a fluid release depending on your seal arrangement.
“So by putting a fire shield on the valve all you’re doing is putting a cover overtop to protect and insulate your seals and bolting. From a design perspective, it’s pretty much a normal valve but we just put those shields overtop the critical elements,” said Brzezicki.
Three P5 Master Flo choke valves with fire shields await shipment from our main facility in Edmonton.
In addition to their standard fire shield made of carbon steel, Master Flo has been able to achieve API 6FA using two designs that utilize seals that can withstand more direct contact with fire. While not as popular as the shield, Brzezicki says the designs do see use in specific applications.
Since choke valves are not isolation devices, as Brzezicki mentioned earlier, it does beg the question why some of our customers are requiring this design and certification for the valves they order.
“There are some specific applications or local regulations that may require this certification,” replied Brzezicki. “There is also a growing trend within the industry and some regions to now include a number of these enhanced safety specifications. As an example, API 6FA for choke valves has now become very common in the Middle East to standardize on this for all applications, as well as some projects in Africa and Indonesia.”
While there is no doubt that a fire safe choke provides an added layer — quite literally — of safety, Brzezicki has had his fair share of interesting experiences as API 6FA becomes more standardized and added to purchase orders, irrespective of the application at hand, and the use of API 6FA becomes more widespread.
“I had one this year where we had a customer who insisted that the valve be fire safe,” recalls Brzezicki. “It was on a water injection valve.”
That peculiar order aside, Master Flo’s ability to provide customers around the world with API 6FA choke valves across a wide array of configurations, is but another capability to add to the impressive list that continues to get longer for the world leader in choke valve technology.