If the pile hammer is to be stored or out of service for an extended period of time, certain precautions should be taken to prevent damage to the hammer and risk to personnel. A storage or resting place should be selected which will adequately...
There are two primary types of noise which are produced by any pile hammer. The first is impact noise produced by the ram striking the pile. The second type of noise is produced by the operating steam or air as it is exhausted from the cylinder...
HIGH TEMPERATURE HAZARDS
Although the pile hammer is constructed of non-flammable materials, the high temperature generated during use can pose a threat to the user if caution is not used. The types of hazards that may be produced are, first, the combustion of materials...
PRESSURE and WEAR FAILURES
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...
The pile hammer should be used only by well trained and experienced personnel. Before using the hammer all instruction and safety manuals should be thoroughly reviewed by all operating and maintenance personnel. These references are an invaluable...
If the pile hammer is to be stored or out of service for an extended period of time, certain precautions should be taken to prevent damage to the hammer and risk to personnel.
A storage or resting place should be selected which will adequately support the weight of the hammer. The site should be level, firm, and a protected area. Keep the hammer off the ground. This can be done by using the original shipping skid or resting the hammer on two 8″ x 8″ wood beams. In addition, because of the hammer’s great weight it should be secured to preclude damage from unexpected movement. The ram should be properly blocked in the down position. This is accomplished by using a 4″ x 4″ timber wedged between the cylinder and the ram and securing the timber to a column with banding iron. The 4″ x 4″‘s should be used on diagonally opposite columns.
After its use, a thorough inspection should be performed. If any defects are found, they can be repaired during the storage period,thus preventing malfunction, danger or on the job downtime.
Before storage, a complete lubrication and rust proofing should be done in order to protect the hammer from the elements and subsfequent corrosion. For further protection, a cover of canvas or plastic can be used to provide shelter, and thus reduce the effects of exposure to the environment.
When the storage period has ended and it is time to put the machine back into service, another thorough inspection, cleaning and lubrication will assure that the hammer is ready for service.
By taking these few precautions, the life of the hammer can be extended, its efficiency can be maintained, and its safety greatly enhanced. Detailed instructions on preparation for storage including inspection procedures and lubrication requirements are given in the Field Service Manual, supplied with each hammer by Vulcan.
There are two primary types of noise which are produced by any pile hammer. The first is impact noise produced by the ram striking the pile. The second type of noise is produced by the operating steam or air as it is exhausted from the cylinder. In both cases, depending upon hammer size, it is possible to produce noise levels which are potentially damaging to the auditory mechanism in the ear.
At present, there are not too many practical ways to reduce these noise levels. In the case of impact noise, cushion material can be used to reduce the noise levels as well as modify the impulse duration as required by soil type and piling composition. The exhaust noise can also be reduced through the use of an exhaust muffler. However, if it is impractical to muffle the exhaust, there are other alternatives which will provide construction personnel with adequate hearing protection. Because sound intensity decreases rapidly as the distance from the hammer increases, simply keep all personnel as far from the hammer as is practical. Obviously, there are many other safety reasons why no one should be near the hammer when it is in use. However, if personnel cannot be stationed far enough from the hammer to adequately reduce the noise, earmuffs or earplugs should be used. If there is concern about the noise level at any job site, it is advisable to use a sound level meter to establish what abatement procedure is needed. It is obvious that the user must give more attention to the noise problem as ever more stringent environmental safety restrictions are imposed by government authorities. Refer to O.S.H.A. Standards 1910.95 and 1926.52, Occupational Noise.
HIGH TEMPERATURE HAZARDS
Although the pile hammer is constructed of non-flammable materials, the high temperature generated during use can pose a threat to the user if caution is not used. The types of hazards that may be produced are, first, the combustion of materials associated with the use of the hammer and, second, burns from contacting the heated parts of the machine. During use, the hammer will get hot as a result of the tremendous energy that is expended with the expansion of steam or air in the cylinder and with each blow of the ram. Although it is unlikely, it is possible that the heat will be sufficient to ignite some lubricants that may be used on or around the hammer. Information regarding the combustibility of the lubricants can be found either on the container or can be obtained from the manufacturer. Keeping the machine reasonably clean and avoiding the build-up of dirt that could absorb oil and grease will reduce the risk of fire.
Cushion material, having been subjected to impact of the ram does experience very high temperatures. There is little chance of most materials actually flaming during use if they are the ones recommended by Vulcan and used in the recommended manner. However, when the material is removed and has access to open air, some materials may burn or come in contact with another material that will burn. Therefore, used cushion material should be stored or disposed of in a place and in such a way that it will not create a risk as a source or transmitter of fire.
During use, for reasons previously mentioned, the hammer can become hot and this heat can be retained for a long while after use. Consequently, during or just after the use of equipment, workmen should exercise caution when in the vicinity of the hammer to avoid being burned by contact with hot metal parts.
When steam is being used, special caution should be used. High pressure steam is extremely dangerous if not treated with respect. Also, condensed steam may drip off the hoses or the hammer and could cause serious burns.
Since there is some chance of fire, an approved type fire extinguisher should be kept on hand at all times and a burn treatment kit should be kept with first aid materials. Being alert and aware of the hazards is a good defense against them.
PRESSURE AND WEAR FAILURES
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.
The pile hammer should be used only by well trained and experienced personnel. Before using the hammer all instruction and safety manuals should be thoroughly reviewed by all operating and maintenance personnel. These references are an invaluable source of information and should be retained by the owner for future study and to train new employees. Copies of these manuals should be kept with the hammer at the construction site for ready access. Additional copies are available from Vulcan.
Safe use of the pile hammer, as with any machine, is dependent upon the skill, knowledge and concern of those who maintain and use it. Because of the wide variety of environments and applications in which this machine may be used, a comprehensive description of detailed rigging and operating techniques within this booklet is not possible. (Specific requirements should be addressed to Vulcan’s engineering department.)
For reasons mentioned elsewhere, no one should be any closer to the hammer during driving than is absolutely essential. All workmen should wear safety clothing including hard hats, safety shoes, safety glasses and hearing protection.
Before, and periodically during usage, a complete inspection should be performed on the hammer and all associated equipment to insure operational integrity. The associated equipment includes items such as the compressor and/or boiler, hoses and hose couplings, leaders, support and lifting equipment and all rigging, etc. On the hammer, particular attention should be given to sheaves, pins, retaining bolts, hose couplings, the valve mechanism, all keys, ram point, pile cap, and the lifting points. Supervisors should be certain that all inspection and maintenance is properly done.
During the driving operation and whenever the hammer is moved, constant supervision and inspection should be provided. If abnormalities are observed, driving should be stopped immediately. One example would be that of the loss of one or more ram keys. If both keys are missing, then the ram would obviously no longer be connected to the piston. Without the ram to slow the acceleration of the piston on the up stroke, the piston may impact into the cylinder head with catastrophic effects. Another dangerous situation would be to continue hammer operation without a piling seated in the pile cap. In this event, the entire force of the falling ram could be absorbed by the hammer’s columns, base and pile cap. Few such strokes could be sustained without severe damage to the hammer. Obviously, such destruction would be hazardous to anyone in the vicinity. Also, the cylinder head lifting points (sheave, axle, pins, keys and nuts) should be continuously checked for worn, loose or missing parts. Damaged or missing components oif this assembly could cause hammer to disconnect from rigging and fall.
The effects of unregulated steam or air pressure may also create a risk. As noted elsewhere, failure of any of the hose couplings, while under pressure, could be very dangerous. In addition, operation at pressures either higher or lower than specified design should be avoided since structural damage to the hammer or inefficient operation may result. Obviously, all air or steam supply hoses must be properly sized to avoid undue flow restrictions.
Damage to the pile, pile cap, ram point and piston can occur if the alignment of the hammer and the pile is not correct. That is, the central axis of the hammer should be in alignment with the central axis of the pile and the pile end should be square and uniform. If the error in alignment is great, the hammer will receive an unbalanced structural loading which could result in either a fatigue failure in the hammer or a significant shortening of its useful life. Obviously, this type of condition could be both expensive and dangerous, but can be avoided with reasonable care.
A common pile driving criterion is to drive until a certain number of blows per foot of pile insertion is achieved. This measure is based on the amount of energy delivered with each stroke of the ram. In a single acting hammer, the energy is dependent upon the falling weight and stroke length. Since falling weight is constant, only changes in stroke length can affect the energy delivered. Therefore, if a variable stroke hammer is used, it should be noted that the blow count taken is compared to the proper stroke energy, i.e., the blow count criterion will vary with the stroke length used. The supervisor should correlate the blow count criterion and the stroke length. Otherwise, pile damage, added expense, or inadequate pile installation could result. It should also be noted that significant deviations in pressure delivered to the hammer from the recommended pressure may affect the actual operating stroke length and thus influence the energy in each blow of the hammer.
Since the pile hammer is such an extremely powerful machine, it is conceivable that even with normal operation, surroundings at the driving site could be damaged. Operators should take every precaution to see that exhaust from the hammer and vibration of the earth are not a threat to the area surrounding the driving site. Failure to do so could be unsafe and possibly lead to expensive property damage.
As an additional precautionary measure, a pre-pile driving survey could be made.
Given the respect it deserves, the pile hammer should provide years of safe service. However, the ultimate safety and reliability of the hammer rest in the hands of the user.