Patuxent 5442.htm

MEMORANDUM OF STANDARD PROCEDURE

PORT HUENEME UNDERWAY REPLENISHMENT DEPARTMENT

PROCEDURE FOR HOT-DIP LUBRICATION OF SLIDING BLOCK DRIVE

CHAINS

Notes:

This procedure developed at the Navy Underway Replenishment Test Site at Port Hueneme.

Procedure developed to be used as a technical specification attached to industrial work orders involving installation of new drive and hoist chains on sliding block drives.

A 55-gallon drum can handle two ten-foot lengths of chain at a time using this procedure. A barrel heater and overhead crane are required. Larger tanks may be used but will take longer to heat and cool for each batch of chain.

Ensure sufficient quantity of make-up lubricant is on hand to augment loss from tank as each chain section is completed. One 55-gallon drum of Mobil ARMA 798 is usually enough make-up product to coat approximately 320 feet of double wide, number 160, two-inch pitch, cotter-constructed American standard roller chain using this procedure. This amount of chain is enough for two Navy standard sliding block drive stations.

Procedure:

Heat Mobil ARMA 798 (a Mobil Oil Company product) to 140-150 degrees F.

In a tank with adequate volume to allow complete immersion of chain sections, heat Mobil ARMA 798 lubricant to a uniform temperature of 140 to 150 degrees F. Stir as required to eliminate any lumps of non-liquid, un-melted grease.

Completely immerse chains into hot liquefied Mobil ARMA until up to temperature.

If feasible and to save time, preheat chain sections to 140 to 150 degrees F. prior to immersing into hot liquid Mobil ARMA. Otherwise completely immerse ambient temperature chains into hot liquefied Mobil ARMA and allow sufficient soak time until chain temperature equals oil temperature of 140 to 150 degrees F. Correct temperature equalization point is achieved when entire length of chain is hoisted completely out of the tank and hot liquefied Mobil ARMA is observed running off with no solid, un-melted grease remaining on any chain surface.

Soak chains an additional thirty minutes, flexing the chain at least three times.

When the liquefied lubricant and chain have equalized at the desired temperature, continue to soak for a period of thirty minutes. Flex the chain to ensure thorough lubricant penetration by hoisting one end until the other end is lifted completely off the bottom of the tank, and then lowering back down. Perform at five, fifteen, and twenty-five minutes. This is required to remove air bubbles and fully impregnate the Mobil ARMA under the rollers.

Remove heat; allow Mobil ARMA and chain to cool to 120 to 130 degrees F.

Upon completion of the 30 minute soak and flex period, remove heat source to allow the lubricant and completely immersed chain to cool down together until a uniform solid coating of lubricant approximately 1/16 to 1/8 inch thick has formed on all external surfaces of the chain. This will be achieved at a chain and lubricant temperature of 120 to 130 degrees F. Periodically hoist the entire chain out of the lubricant to observe the gradual transition from complete liquid runoff to an increasing buildup of solidified grease.

This step is required to prevent all the Mobil ARMA from draining off the chain when the chain is removed from the bath. No additional top coating of the chain should be necessary except for minor touch-up of any surface disturbed during assembly and installation of the chain.

Remove chain sections from bath.