x The margin between normal working pressure and the safety valve pressure; x The sinking-time of the boiler, i.e. the time during which the water level will sink from the lowest permissible water level to the highest point of the heated surfaces. This may involve consideration of an automatically closing valve on the steam outlet so as to prevent steam export; x In some installations, there may be exceptional environmental or operational implications to testing of boiler controls. Testing regimes should be established to ensure that the controls and trips can be proven without tripping the plant except under controlled conditions as justified by a risk assessment. 8.6 Feed water and boiler water checks A water treatment specialist shall undertake regular checks on the water treatment plant and test the feed water, boiler water and condensate quality. If scale is found in boilers, the water treatment system should be checked for correct operation and appropriate corrective action taken immediately. In addition, a suitably trained and competent employee or the boiler operator shall make the following checks, usually on a daily basis unless suitable automatic testing/monitoring and a supporting risk assessment is in place, in which case a frequency of up to 72 hours might be acceptable: x That the feed tank level is adequate and there are no contaminants; x That the feed tank temperature is above the required level for the chemical water treatment dosing levels, specified by the water treatment specialist, for complete oxygen scavenging; x That any chemical dosing metering device is functioning and there are adequate chemical stocks, both in the tanks and elsewhere on site; x That in-house routine sample results are within their given parameters provided by the water treatment specialist and/or any recognised standard including BG04, BS 2486:1997, BS EN 12953- 10 or the manufacturer’s instructions , and take remedial action when and where necessary. In-house routine testing is expected to include at least the following: o oxygen scavenger reserve; o alkalinity tests; o pH; o hardness checks of softening plant, feed tank, and boiler; o total dissolved solids level within the boiler; o appropriate tests of the condensate; o that the temperature is above the required level for the chemical water treatment dosing levels, specified by the water treatment specialist, for complete oxygen scavenging; o other tests as determined by risk assessment. For more detailed and specific guidance please see BG04, BS 2486:1997, BS EN 12953-10 or the manufacturer’s instructio ns. Unless risk assessment demonstrates otherwise the minimum frequency of checks on the feed and boiler water shall be the same as the minimum attendance requirement on the boiler when operating. Special consideration shall be given to the water treatment requirements for reserve boilers and boilers that are to be left unused for any period.
BG01 Guidance on the safe Operation of Steam Boilers Edition 2 – © 2019
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