What I am going to suggest in this article is NOT necessarily a code or standard requirement, but just some SOUND ADVICE on how to improve safety around expansion/seismic joints where hoses are utilized to allow for flexibility. As my clients know, I HATE hoses in a chemical process and I am OCD when it comes to the required utilization of hoses such as loading/unloading hoses. I am a huge fan of The Association for Rubber Products Manufacturers (ARPM) RAGAGEPs for the use and maintenance of all hoses used in a chemical process. But this article will focus on some very short run of a “hose” called an “expansion loop” or “seismic shift” protection where the hose is embedded into a pipe run so that should the pipe need to flex/move, the hose allows this. But these short runs of hose are often forgotten about and many will assume the hose is equal to the pipe in its ability to withstand atmospheric and process conditions. Back in my days in Petro-chem plants, I had a large LOPC incident involving an HHC/EHS from one of these hoses failing. What I learned from that event has stayed with me till this day and now I want to pass it on to you and your engineering team for consideration…
#1 – the hose MUST be in the Process Safety Information with its documented for materials of construction and pressure ratings.
#2 – the hose MUST be in the Mechanical Integrity for change-out frequency, inspection/testing, etc.
Here is my advice on the pipe/hose design: (See reference to the IFC, Chapter 50 below)
At the inlet of the hose connection, we install an excess flow valve in the pipe sized to the pipe/hose flows. Should the hose fail catastrophically we have a safeguard to stop the flow at the leak point. We should also have an emergency shutdown valve further back in the pipe run that would be used to isolate the hose from a “safe distance”.
On the outlet of the hose connection, we install a “check-valve” in the pipe. Should the hose fail catastrophically, the check-valve will isolate the leak point and prevent the HHC/EHS from flowing back to the leak point. We should also have an emergency shutdown valve on this side of the hose that would be used to isolate the hose from a “safe distance”.
Remember, excess flow valves and check valves are not highly reliable safeguards, so we install them but we do not put all our faith in them functioning; thus we have the emergency shutdown valves identified in the field and in our emergency shutdown SOP.
In my event, we lost a lot of HHC/EHS because we were NOT prepared. The company revised its engineering specs and the business went back and installed these safeguards and they worked, as several years later a similar event occurred and the LOPC was not even a “reportable release”. So we took an event where we lost thousands of pounds of the HHC/EHS down to less than 100 pounds lost in the exact same LOPC event. Throw in the fact that we did not have a long drawn out emergency response and did not have to put anyone in harms way – this simple design is a WIN-WIN no matter how you look at it. Maintenance had the hose replaced, pressure and leak-tested, and the unit was back online as soon as we had completed our investigation and failure analysis of the hose. From that point on, I had that design embedded into my brain and every time and I see an expansion hose I go back to my chlorine days and think ALL HHC/EHS pipe runs with these hoses should have this design. But again, this is NOT a RAGAGEP requirement, just a neat design that a wonderful engineer came up with at some time at some plant and it has migrated through an industry as a “best practice”.
PLEASE NOTE: this design is in the International Fire Code (IFC):
IFC, Chapter 50 – HAZARDOUS MATERIALS—GENERAL PROVISIONS
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5003.2.2 Piping, tubing, valves and fittings. Piping, tubing, valves, and fittings conveying hazardous materials shall be designed and installed in accordance with ASME B31 or other approved standards, and shall be in accordance with Sections 5003.2.2.1 and 5003.2.2.2.
5003.2.2.1 Design and construction. Piping, tubing, valves, fittings and related components used for hazardous materials shall be in accordance with the following:
1. Piping, tubing, valves, fittings and related components shall be designed and fabricated from materials that are compatible with the material to be contained and shall be of adequate strength and durability to withstand the pressure, structural and seismic stress and exposure to which they are subject.
2. Piping and tubing shall be identified in accordance with ASME A13.1 to indicate the material conveyed.
3. Manual valves or automatic remotely activated fail-safe emergency shutoff valves shall be installed on supply piping and tubing and provided with ready access at the following locations:
3.1. The point of use.
3.2. The tank, cylinder or bulk source.
4. MANUAL EMERGENCY SHUTOFF VALVES and controls for remotely activated emergency shutoff valves shall be identified and the location shall have access clearly visible and indicated by means of a sign.
5. BACKFLOW PREVENTION OR CHECK VALVES shall be provided where the backflow of hazardous materials could create a hazardous condition or cause the unauthorized discharge of hazardous materials.
Exceptions:
1. Piping for inlet connections designed to prevent backflow.
2. Piping for pressure relief devices.