Kingfishers' findings on Imported Grease Fittings

Samples were obtained of imported grease fittings which are being offered as a cheaper alternative to Kingfisher. These parts (1/8” x 28 BSP Straight) were examined and the following was found:-

  1. The parts were not hardened. They should be case hardened.
  2. Some of the threads were very slack in the 1/8×28 BSPF no/go gauge. This may lead to leakage around the threads.
  3. The flank angle of the thread was 60°-65° (it should be 55°)
  4. The shank length compared with DIN71412 was too short at 4.5mm (it should be 5.0-5.5mm)
  5. The lip was too long compared with DIN71412 at over 1mm (it should be less than 0.7mm)
  6. The edges of the parts look very rounded as if they have been in acid for a long time (possibly as when they were cleaned as part of the plating process)

When 2 parts were grease tested it was found that the opening pressure which was initially 230psi and 160psi dropped to 150psi and 60psi. After a high-pressure test at 8000psi, a large drop like this could indicate that the spring may fail with repeated use.

When the 2 parts were leak tested at 5000psi, one leaked all its grease past the ball. The other part leaked out of the neck! When this part was sectioned, it was found that, although the ball check was central, the internal drilling was very off centre and the neck wall was very thin and had cracked.
This failure could result in serious consequences. If the head completely snapped off during greasing at pressures of up to 8000psi, the resulting release of grease could cause serious injury.

Chinese Grease Fitting Failure Grease Nipple Manufacturer
Chinese grease fitting cracked part Grease Nipple Manufacturer

The internal drilling was very off-centre and the neck wall was very thin and had cracked.

Chinese grease fitting drilling Grease Nipple Manufacturer

Three further fittings were sectioned, and the drilling was found to be badly off in 2 more of the fittings.

Chinese grease fitting internal Grease Nipple Manufacturer

The finish inside some of the fittings was extremely bad, and also of note is the ball lands on these parts are very thin or non-existent