The Association for Rubber Products Manufacturers (ARPM) is an organization that was started in 2010 after elastomer products company executives belonging to the RMA mutually agreed that a stand-alone association was needed for codes/standards. Those of us in the process safety field are all too familiar with the RMA and ARPM, as these organizations write the “holy grail” RAGAGEPs for hazardous material hoses. In this article I want to update those of you who handle Anhydrous Ammonia (NH3), as IP-11-2, MANUAL FOR USE, MAINTENANCE, TESTING, AND INSPECTION OF ANHYDROUS AMMONIA HOSE has been revised and this standard is one that can be ADOPTED immediately for the hoses in service and new hoses. IP-11-2 holds a few surprises for us, so let’s jump right into it…
Anhydrous ammonia hoses have limited life, and the user MUST be alert to signs of impending failure. The periodic inspection and testing procedures discussed in this article provide a schedule of specific measures which constitute the MINIMUM requirements necessary to detect signs indicating hose deterioration or loss of performance BEFORE a failure occurs.
One warning provided in the standard states: (emphasis added by me)
Anhydrous ammonia hoses can NOT be recoupled under any circumstances!
This may be new for a lot of facilities as I know the practice of making and repairing one’s own hose(s) was/is relatively common.
The scope of the standard is intended to apply to hoses used to convey NH3 liquid or gas between tank cars, storage units, and trucks, having inside diameters up to and including 3 inches (76.2 mm).
DAILY VISUAL Inspection(s)
Prior to the day’s use, a VISUAL inspection MUST be conducted. If any unusual appearances are noted during this inspection, the hose MUST be subjected to a hydrostatic pressure test as described below.
All NEW HOSES MUST be tested PRIOR to use to determine if they have been damaged in STORAGE and/or SHIPMENT.
- When the hose is intended for “Normal Use” (i.e., the hose is subjected to ordinary use) the frequency of hydrostatic testing shall be ONCE EVERY 90 days for the FIRST YEAR and EVERY 30 DAYS thereafter.
- When the hose is intended for “Severe Use” (i.e., hose subjected to severe usage such as dragging over sharp rock surfaces, sharply bent in torque, or continually exposed to weather), it MUST be hydrostatically tested EVERY 30 DAYS from the date of installation.
SAFTENG NOTE: The “abnormal use” scenario discussed above could very easily be an NH3 unloading/loading hose that stays connected to the process, remains outside between uses, and the unloading/loading area is graveled. If this describes the usage area, then the hose inspection protocol SHOULD be managed as “Abnormal Use” (e.g., hydrostatically tested EVERY 30 DAYS)
Hoses MUST BE be HYDROSTATICALLY TESTED IMMEDIATELY AFTER the hose is subjected to ABNORMAL ABUSE such as severe end pull.
Hose flattened, crushing by vehicles, or subjected to a sharp kinking shall be REMOVED FROM SERVICE.
Visual Inspection Procedure
All physical testing shall be performed with the hose at ROOM TEMPERATURE. An “inspection card” for the hose shall be maintained which describes:
- the hose,
- the manufacturer,
- date received and date placed into service
- purchase order number
- results of hydrostatic pressure test(s) and
- visual inspection with date and signature of person performing the work
All entries on the “inspection card” MUST BE legible.
A hose with cuts which EXPOSE or DAMAGED the reinforcement would FAIL the inspection, and it MUST be removed from service. However, a hose with small cuts, nicks, or gouges in the cover which have NOT completely gone through the cover would not fail the inspection. The basic premise for this is that the hose strength is controlled by the plies of reinforcement and, for this reason, any damage in this area can NOT be tolerated.
Hoses with a textile reinforcement or wire braid and these have any signs of damage, the hose FAILS. A wire braided reinforced hose which has either been kinked or flattened, to permanently deform the wire braid in an unpressurized state, MUST be removed from service.
Blistering or loose outer cover also FAILS the hose.
Hydrostatic Pressure Test
AFTER a hose has completed its visual inspection, the hose must be “pressure tested,” and in order to do so, it must be connected to a test pump capable of producing at least 700 psi. The hose will be placed in a straight line and pressured to 200% of the WORKING PRESSURE recommended by the hose manufacturer. We hold the test pressure for a MINIMUM of five (5) minutes and while under pressure, the hose MUST be examined for leaks, especially near the couplings and any noticeable bulging or swollen areas. Any leaks or bulging spots and the hose FAILS the test.
Seems simple enough… make sure we establish the “use” rating of the hose (e.g., “normal” or “abnormal”) and then based on this decision
CLICK HERE to order your copy of IP-11-2, MANUAL FOR USE, MAINTENANCE, TESTING, AND INSPECTION OF ANHYDROUS AMMONIA HOSE