THE REDUCING VALVE.
COURT OP SURVEY'S DECISION.
The Chairman (Mr. T. Hutchison, S.M.) of; the Court of Survey, held at Greymouth to hear an appeal by the Greymouth Harbour Board against a decision of the Chief. Surveyor of Ships at Wellington, delivered his reserved decision as follows: "The history of this matter appears to be as follows: In 1915 the appellant Harbour Board upon the advice of its officers determined to instal a new boiler, which would give more power, in the tug Westland. Accordingly, in 1916, the Board imported ami installed in the tug a Babcock and Willcox Avater tube boiler having a boiler pressure capacity of 1501 b. to the square inch, reduced by means of an Auld reducing valve to a working pressure of 1001 b. This boiler was inspected by the local inspector (Mr. Peter McKenzie), who made his declaration' thereupon on January 6t"i, 1916, by which declaration the boiler was approved allowing a pressure o± 1501 b., with a reducing valve set to apply to the engine, a pressure of 1001 b. The declaration was altered in Wellington, by which the high pressure certificate was issued accordingly. The Board did not appeal against this certificate because it was advised that an appeal only lay against the inspecting engineer's declaration. Upon the 'inspection of the boiler in 1917, Mr. McKenzic considering that he was bound to follow the Department 's alteration of the previous year, but against his own judgmtnt, made his declaration in accordance with the previous altered declaration. It is against this declaration that the Board now appeals. The question raised by the appeal appears to be whether the type of boiler with a reducing valve introduced should be allowed. " . !No evidence beyond the formal evidence of Mr. MeKenzie was called beforo me by the Department'; but a large body of evidence was called on behalf of th e Board. That evidence all went to show that the water-tube type of boiler when suitably installed was perfectly safe; and that the Babcock and Willcox boiler now installed in the -Westland with the reducing valve litted in connection therewtn was quite efficient for the reduction oi the high pressure generated in the boiler to the lower pressure required for the engine. Mr. Duncan, Chief Inspector of Machinery, who appeared for the Department, stated that theDepartmental objections to th e use of a reducing valve were as follows: (1) Generally, the uncertainty of such valves at times and the danger, at a critical jtime if it should fail to act. (2) Specifically, its use on a tug— a one-man boat — working on a dangerous coast. Mr. Duncan cited a large number of authorities from the" official reports upon boiler explosions in 1 , England. I have read all the excerpts troni such reports handed in to the Court. The whole of them go to show that reducing valves are not to be condemned per se; but that in their use they ought to be accompanied by an efficient safety valve of sufficient size fitted upon the low pressure side of the reducing- valve. The Court has made an inspection of the tug Westland and the two assessors have in addition had an actual demonstration of: the working of the machinery of the tuaf under steam, and at sea. The tug crossed the bar and the operation _ of. the reducing valve was closely ™ watched by the assessors. Their conclusion was that the tug in respect of it machinery was in every way satisfactory. There is at present attached to the steam rpceiver on the low pressure side of the reducing valve a safety valve. This should be replaced by a valve having an area in excess of the area of the steam pipe, and fitted with a waste steam pipe to carry away the waste steam clear of the engine- * room. With this alteration the last and only reasonable objection to the use of th e Auld reducing valve would be removed. I therefore conclude that the proper order to make on this appeal is that upon there being fitted the steam receiver a lock-up spring loaded safety volve having two separate and independent valves of equal area, but the. total area to be in excess of the area of the main steam pipe to which it is fitted, and such valve having a waste j steam pipe so arranged as to carrythe_ waste steam clear of the engineroom, and then upon such valve being set and locked for a pressure of 1001 b. to the square inch by the local surveyor, a certificate is to issue allowing a boiler pressure of 1501 b. to the square inch, reduced' to 1001 b. at thtengine. The above decision is also signed by the assessors (Messrs W. J. Le Cren and EdgaT P. Turner^ of Christchurch). Costs amounting to £52 r lls were allowed appellants, on behalf of whom Mr. F. A. Kitchingham appeared.
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Bibliographic details
Grey River Argus, 16 May 1917, Page 4
Word Count
824THE REDUCING VALVE. Grey River Argus, 16 May 1917, Page 4
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