Most of my clients who are users of Chlorine (Cl2) use it in vacuum systems where the Cl2 is being injected or inducted into a water flow. In these smaller “processes” it is not unusual to find “tubing” being used vs. hard pipe. It took me years to accept the tubing design model as I was always raised that Cl2 is a Category M Hazardous Material per AMSE B31 and thus the piping had to meet additional installation parameters above and beyond say what Anhydrous Ammonia piping would have to meet. So to say I was taken back when I walked into the first Cl2 Cylinder room/building as a consultant and saw a lot of “tubing” being used is a bit of a stretch – luckily I was with an old friend who hired me to help with his Cl2 process.
As both OSHA and EPA requirements, when it comes to the Mechanical Integrity of our containment systems, we start with the manufacturer’s requirements…
1910.119(j)(4)(iii) The frequency of inspections and tests of process equipment shall be consistent with applicable manufacturers’ recommendations and good engineering practices, and more frequently if determined to be necessary by prior operating experience.
or
§68.73 Mechanical integrity
…
(3) The frequency of inspections and tests of process equipment shall be consistent with applicable manufacturers’ recommendations and good engineering practices, and more frequently if determined to be necessary by prior operating experience.
And with this tubing, we have some STRICT manufacturer’s replacement frequencies…
Polyethylene tubing is the most common material of construction for this Cl2 tubing and MOST, if not all of the companies who sell this tubing for chlorine service, will specify “it should be inspected regularly for cracking and replaced at least once every two years“. There are those two squirrely little words again… “at least”. So we have to inspect the tubing “regularly” and replace it (regardless of inspection results) at least every two (2) years. And with any such practice, I ALWAYS suggest that the hose/tubing be tagged with its IN-SERVICE Date so as to be certain we are meeting these change-out frequencies. This tagging is NOT an OSHA or EPA requirement, it is merely a tool we can use to ensure we are maintaining our primary containment system within the confines of the manufacturer’s timetables. Without this tag, anyone who wants to verify the hoses is less than 2-years old would have to do some digging in the MI CMMS in order to find the Work Order as to when the tubing was changed. I have one client who has an actual sign posted in their Cylinder Building that states when the tubing was changed as their practice is to change it annually at each annual turn-around.
This is from one of my favorite Cl2 piping/tubing providers: (emphasis by me)
| Vacuum lines for chlorine gas service usually are constructed of polyethylene tubing, PVC pip-ing (Schedule 80 PVC), or any other appropriate material recommended in the Chlorine Institute’s pamphlet 6 “Piping Systems for Dry Chlorine”. XXXXXXXXXX provides a tubing and piping sizing guide to aid in selection. If polyethylene tubing is used, it should be inspected regularly for cracking and REPLACED AT LEAST ONCE EVERY TWO YEARS. Wherever possible, PVC piping joints should be socket glued rather than threaded because threaded joints are much more likely to crack. All threaded joints should be wrapped with Teflon tape. Care should also be taken not to over-tighten plastic joints and crack the material. |