Although unlikely to occur under normal operating conditions, hose failure can cause substantial injuries to personnel and property since the steam or air pressure used is typically over 100 PSI. This line pressure, when distributed over a few square inches of area, generates a tremendous force which will cause an unsecured broken hose to whip in a violent unpredictable way. Since such a condition could produce a substantial injury, precautions must be taken to see that this does not occur.
The air/steam supply hose should be secured to the hammer by heavy chain or rope of adequate strength (refer to O.S.H.A. Standards 1926.251), attached to the anchor point on the hammer with a shackle. Inspection of this connection should be made at the beginning of each shift and after the driving of each pile.
Another critical point of the hammer is its valve mechanism and as such, requires regular inspection and maintenance. With normal functioning, air or steam is admitted to the cylinder and released in alternating cycles. After release, the ram falls and impacts with the pile cap. If steam or air is not permitted to enter the cylinder freely or if it is not relieved, there is a possibility that a major structural problem could occur.
The valve mechanism could be jammed by foreign material or it could be broken through misuse or improper handling. However, regular inspection, cleaning and lubrication will reduce the likelihood of trouble. Nevertheless, special attention should be given to the slide bar and wedges, the valve, and the actuating levers at each opportunity. At all times, personnel should stay clear of the hammer until the ram is resting on the base.
Complete inspection and maintenance should be performed at the beginning of each shift and/or after the hammer has been inoperative for over an hour. Cylinder head nuts, the head itself, the cylinder and columns should be given attention. All keys wear and loosen with use and should therefore be checked and secured after each drive. Since they are heavy, a key could be dangerous if it should be dislodged and fall from the hammer. In addition, if both ram keys should be lost during use, the ram would not be secured to the piston and without the inertia and weight of the ram to retain it, the piston could be driven through the cylinder head. Therefore, key condition is obviously very important for safe operation and should be carefully maintained.
Because of wear that occurs during prolonged use, the ram point and pile cap may fragment from metal fatigue. This fragmentation will be accelerated by improper use, such as by misalignment of the hammer axis with the pile and by using a pile cap of inappropriate size. The fragments may be violently ejected during driving and could be a threat to personnel safety. Therefore, both the ram point and pile cap should be checked after each drive and if excessive spalling or cracking is found, should be repaired or replaced. It is essential that the axis of the hammer be closely aligned with the axis of the pile and that the pile cap should be matched to the size of the pile being used. All personnel should remain well clear of the hammer during use, reducing the risk of being struck if fragmentation should occur.