If the pipes are continually knocking or banging it may be that the pressure fluctuation is causing vibration - If those pipes are not supported (clipped in to a rigid position) they will effective bang against each other or against flooring/wall supports.
If they are sealed units check for air locks in the circuit - this frequently caused such noises, Also check the steam feed is uninterrupted - The effect in the pipes would be like a steam piston which builds to high pressure only to release in a sudden burst
-- Also excessive condensate in the steam piping will cause knocking, usually due to improper pitch of the piping not allowing the condensate to drain properly.
I have been unable to turn up any information whatsoever about anything called a 'steam coil hammer.' Is it possible you've gotten your terminology mixed up? I am hoping the following research might provide you with a satisfactory answer. [from dictionary.com] - a coil of pipe, or collection of connected pipes, for containing steam; -- used for heating, drying, etc. - A banging noise heard in a water pipe following an abrupt alteration of the flow with resultant pressure surges; A banging noise in steam pipes, caused by steam bubbles entering a cold pipe partially filled with water. And according to information found here Steam Coil Installation, Operation and Maintenance (PDF), if a steam coil is not mounted properly, water-hammer can be destructive to the coil(s) It is entirely possible that the term 'steam coil hammer' simply refers to the banging of steam coil pipes. I'm not sure this is what you were after. If not, if you can provide more details, perhaps I can do a little more research and find the answer you need.
In a steam heating system, the pipes transport steam or water vapor to the radiators to heat the building. Insulating the pipes reduces the amount of heat lost to the surrounding environment. Any heat lost in the pipes cannot be used to heat the radiators, and causes the system to be less energy efficient.
air in the water lines causes banging and whistles/screams. Turn off main water, turn on the faucet, turn main water back on, and it should force the air out.
Bleed the accumulated air out of the system. I did it twice a year, to improve heating efficiency, and eliminate banging noises.
steam pipes.
I'm not familiar with rumbling in pipes, but the clanking of pipes when the heat starts up is a result of the pipes expanding because of the heat. Heat causes the metal to expand slightly, and the joints creak and clank when the heat makes its way through the pipes.
The steam flows through a grill of pipes and the heat radiates from the pipes to the room.
Steam carrying pipes
avoid the pipes that shoot steam it will happen in the third and fifth rescue.
Ask This Old House - 2002 Banging Pipes Installing Fiberglass Door 7-19 was released on: USA: February 2009
Through steam pipes.
It does things to the things in the things the pipes are made out of if you get me