Tips on keeping your API Loading Couplers working better and longer.

Hints for longer coupler service

• Make sure that there is a check or pressure relief valve to prevent pressure from being locked-in between the coupler and up-stream shut-off valves.  Thermal pressure build-up causes poppet breakage.
• Balance all hose loaders and adjust hose lengths so that the coupler is at the truck adapter height with the primary arm horizontal.  Having the coupler too high or too low causes uneven coupler body wear and increases the chances of poppet O-ring damage (old style).
• Leaking couplers while coupled are usually caused by damaged to the nose piece O-rings, broken wavy washer(s), severely worn locking lugs or a damaged or worn truck adapter.
• Couplers leaking while disconnected usually have a damaged poppet O-ring.  Check the three poppet guides and the mating body area for excessive wear.  A sloppy poppet has more chance of interfering with the truck adapter.  Some O-rings have a line around them from the mold joint.  When installing O-rings, use a lubricant and avoid twisting that causes the joint to fall into the sealing area.
• Keep coupler levers in good condition and installed with the correct pins (no nails!).  A sloppy handle will cause expensive damage to the sleeve and also make the coupling-up more difficult.

Check with PPM for all your OPW and Emco Wheaton API Coupler, Loading Arm, Swivel Joint, Hose and Strainer needs. Contact us here

Thermal expansion can be expensive and dangerous

A major source of coupler leakage problems is due to over-pressure of the hose or loading arm assembly.  This is often caused by pressure build-up from thermal expansion of the product in the arm or hose.  This will result in the hose becoming very stiff.  Thermal expansion problems are normally much worse with arms that are of all-pipe construction.  Arms without hoses have no expansion capacity.

Liquid MUST NOT be shut in or locked in the system.  A relief or check valve should be piped around all up-stream valves.  This will allow any thermal pressure developed at the coupler to be relieved back to the supply tank.

Failure to provide thermal relief in the system can unseat O-rings from their grooves due to the high liquid velocity when the coupler is next opened.  This can result in the O-ring becoming caught up at the truck adapter when attempting to close the coupler.  Poor truck fittings often get the blame for this type of failure.

The mode of failure in the more severe cases depends on the type of coupler.

OPW - The OPW 1004 coupler will stretch the bent links an distort one or more of the three keeper washers.  The poppet is no longer pulled completely back into the coupler body when the valve is closed.  This prevents the coupler from mating up with the adapter on the truck.

EW - The holes in the bent links of the Emco Wheaton couplers will normally wear and become oval.  This also results in the poppet not being fully pulled back into the coupler.  Again, this will make it difficult to mate the coupler with the truck adapter.  In severe cases, the poppet will break at the link pin and part of the poppet can be "fired" 30 or 40 feet.

THERMAL EXPANSION CAN BE EXPENSIVE AND DANGEROUS

We have often have customers bring up the problem of product dripping from API couplers in diesel service.  Frequently we have been told that diesel will seep and that it is impossible to prevent dripping.  To find out how couplers performed, we conducted tests on an OPW 1004 coupler and an Emco Wheaton J451-011.  Both couplers were used and had some wear.  They were inspected to ensure that all the viton seals were not damaged and that there were no defects in the sealing surfaces.

Each coupler was laid face down and filled with diesel and a metal plate was then bolted to the flange.  Air pressure was applied in 10 PSI increments up to 80 PSI and the coupler was inspected for leakage.  None was found on either coupler.

Tests were conducted at higher pressures using a grease gun.  The pressure was increased in 50 PSI increments up to 300 PSI. with no product leakage.  Under these tests conditions the assembly becomes very temperature sensitive.  One coupler was left pressurized for seven days and the pressure was seen to vary between 50 and 300 PSI with variation in temperature.  No product leakage was observed; however, some damage was caused to the internals leaving the poppet slightly extended.

It was concluded that, provided the viton seals are not damaged, NO SEEPAGE occurs and any dripping is due to the residual left from uncoupling after loading.

The more recent OPW 1004D/D2 and the EMco Wheaton J451-021/031 couplers are less prone to dripping due to the reduced "hold-up" by virtue of the seals and poppet design.  These couplers should be used in the diesel service rather than the older OPW 1004 or Emco Wheaton J451-001 or 011.

Contact PPM for your OPW or EMco Wheaton API Coupler, Loading Arm, Swivel Joint, Hose and Strainer Needs