The Natural Refrigeration

The testing or replacement interval for pressure relief valves that discharge back into an ammonia refrigeration system, commonly known as “internal relief valves,” may be redefined based on a new IIAR research project that aims to collect the valves from members and test them.

The project, which is currently underway, is being managed by IIAR staff and members of the IIAR research committee and is being carried out by  ioMosaic, a process‑safety engineering firm that provides testing for the petrochemical and chemical industries.

Eric Smith, IIAR Vice President of Technology, Advocacy, Research and Publications, said the project is unique because it is a direct response to concerns voiced by federal regulators, who have challenged the concept that the valves will not ever fail to open, and because of IIAR staff’s direct involvement in implementing the project.  

Bill Greulich, IIAR’s Research Committee Chair, said the project is necessary because IIAR-6 defines specifics for safety relief valves that discharge to atmosphere, but is essentially silent on relief valves that do not discharge to atmosphere, which generally means that the industry does not regularly replace them.

For many years, there has been no defined inspection or replacement interval because it has been assumed that these valves will always relieve overpressure because they are not exposed to oxygen and water and should not corrode internally. But recently OSHA inspectors began to raise the issue as a discrepancy they expect industry to address.

“OSHA has a point; forever [is probably not] an acceptable period of time,” said Greulich. “This is a great example of a research problem that came in the door through the regulatory side of the industry and is being answered by this project.”

Greulich added that IIAR staff member Matt Chojnacki has been managing the collection of donor valves internally on behalf of IIAR, which is a first for an IIAR research project.

“This is the first time we’re using staff as a major player for the administration of a big project. It’s a great model for us to follow moving forward,” he said. “This is an example of our industry coming together to address a problem for regulators, and it improves our relationship with them because we’re listening to them and interacting with them on this. The standard is silent where there is a perceived issue. Valves are safety devices and safety devices should likely have testing or replacement intervals, so this is a silence we can answer.”

IIAR’s staff leader for the project, Matt Chojnacki, IIAR’s Technical Project Specialist, agreed with Greulich that the significance of the project extends beyond simply getting an answer on replacement intervals.

“This is a group effort to solve an important question, and it concerns nearly everyone,” said Chojnacki. “Our industry has been getting questions on this subject, and regulators are looking for our support on this, essentially asking ‘what’s the requirement?’ There’s an opportunity for us to take the leadership role in answering.”

IIAR’s Smith said, “When OSHA regulators first approached us with this concern, we decided that rather than adopt some arbitrary interval or some interval from another industry, we should first study whether such valves fail or not, and if so, what the appropriate testing or replacement interval for the conditions unique to our industry should be.”

”The IIAR Standards Committee recognizes that opening a system introduces some risk, so applying some testing and replacement interval that may or may not improve safety did not seem appropriate.”

Smith recently met with federal officials to update them on the steps IIAR is taking to address their concerns and reported that they are pleased with the response and will patiently await results, Smith said. “This is a far better approach than either regulators fining the industry or IIAR adding arbitrary requirements.” 

Chojnacki said the research data generated by the project will help IIAR prove or disprove the industry’s current approach to replacement intervals and may reveal that they should be defined in IIAR-6 along with those for valves that discharge to atmosphere.

ioMosaic’s analysis will estimate failure rates of internal relief valves by examining a broad sample of valves donated by IIAR members. So far, nearly 100 valves have been collected. Chojnacki said that IIAR appreciates the participation of members so far, but the project still needs more donor internal relief valves to study, especially ones that have been in place longer and have more wear to examine.

Both liquid and vapor donor valves are welcome and if members know of internal relief valves that will be replaced as a matter of routine maintenance, IIAR would like to have them for the project, said Chojnacki. The project seeks valves from all types of facilities and conditions, whether they are well maintained or not.

So far, the call for participation in the project is getting steady but minimal response from IIAR members, said Chojnacki. The collection process is slow precisely because of the problem the project is meant to study – IIAR doesn’t specify a replacement interval, so there aren’t many valves coming off systems in the first place.

Nevertheless, Chojnacki said he is confident the industry will step up to the challenge and help define the replacement interval problem as word of the project gets out. IIAR is offering a big incentive for participation – free registration to the IIAR Annual Conference (an approximate $800 value) for one (1) person from the donor facility, and one (1) person from the contractor who completes the valve replacement (if a contractor is used). IIAR is also covering the shipping costs to the research contractor.

“I want to call on anyone who can participate to send us their old internal relief valves,” said Chojnacki. “Ultimately, the more data we can yield around this subject, the better it is for our industry. As a driver of this data, IIAR can go back to OSHA and EPA with more than just a gut feel or a disagreement. This is a chance to take it a little further and give them actual data points and proof in support of our stance, whatever that evolves into.”

Every valve an IIAR member can contribute adds to the strength of our position with regulators, he said. “We need these data points, and it’s up to IIAR members to pull through for each other and help us get them.”

David Blake, senior consultant for ioMosaic, agreed with Chojnacki that the project still needs more input from the industry to be successful because of the way the valves are being measured.

“We want to try to determine how long a valve can survive and still be in good service so we [will] look at that data and develop standard deviations,” said Blake.

“We’re looking to try to define a corrosion rate. The problem will be that [for valves with limited years of service] we may not see enough corrosion to measure a difference. The primary data point we’re looking for is failure rates,” a data point that is easiest to collect in older valves.

For now, data collection may be slow going, but Greulich said IIAR understands the obstacles and will work methodically to overcome them.

“There’s no really obvious solution for getting valves from people with no incentive to open up their systems, and that sort of encapsulates the broader issue,” he said. “There are dangers and costs of replacement. Many of these valves were not installed with the idea of maintaining them as we do for external relief valves.”

For that, there’s no simple fix, and it may be the larger issue that the IIAR research project and ioMosaic can help solve on behalf of the industry, said Greulich, adding that ammonia refrigeration differs from most of the rest of the process safety world in the practice of putting internal valves in place and then leaving them there.

“We’re different in that these valves are cheap and small, and we’re used to leaving them in place, but that’s not how other industries [that OSHA and EPA are used to regulating] do it.”

“Now it’s become a matter of aligning our industry with the expectations of our regulatory community,” said Greulich. “Their expectations are formed in the broader process and chemical industry world. We need to get our heads wrapped around what our own data says about replacement frequency.”

That means the success of the ioMosaic project will hinge on IIAR’s ability to get more, older, internal relief valves to measure. “The key in my mind is to get more valves,” he said. “This is a good and earnest thing for our industry to really come together on so that we can close up an open gap in our code.”

If you can contribute internal relief valves to the project and would like to participate, please contact:

Matt Chojnacki, matt_chojnacki@iiar.org, or Eric Smith, eric.smith@iiar.org