In the run-up to the heating season, start-up dangers are a serious problem for many heating systems using steam as a heat source, warns Spirax Sarco, ‘largely due to them having lain dormant over the summer’.
John Pickering, an expert in safe procedures for steam distribution systems at the company, warns that boilerhouse operators must be wary of the threat posed by water hammer and thermal pipework expansion when restarting their boilers. He said: “After a long, dormant period, both water hammer and thermal expansion pose a real threat to steam pipework when systems are fired back up. Water hammer may be viewed largely as an acoustic problem, but the consequences can be much worse. “Entry of steam into a pipe that already has a build-up of water can cause condensation, resulting in a vacuum forming. Water will then rush through the pipe, and its momentum can cause extensive mechanical damage to pipework and fittings.” He added: “Thermal expansion occurs when the steam system is heated too quickly, and the pipework quite literally buckles under the pressure of the steam as it hits the weakest point in the distribution line.” Spirax Sarco recommends an 11-point procedure for warming pipework from cold, as outlined by the National Industrial Fuel Efficiency Service in its Boiler Operator’s Handbook.
