Standard Technical Features of BTG System for Supercritical 660 ...
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Standard Technical Features of BTG System for Supercritical 660 ...

Standard Technical Features of BTG System for Supercritical 660 ... Standard Technical Features of BTG System for Supercritical 660 ...

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Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units9. Material P-22 is applicable for piping with temperature > 510 0 C andupto 550 0 C and P11 is applicable for all other alloy steel piping below510 0 C.10. Materials for fittings, specialties and valves shall be corresponding topiping material or equivalent.18.1.8 Specific requirementsi) Manufacturing tolerances on pipe diameter (for both ID and ODcontrolled pipes) and thickness shall be as per ASTM A-530/ A999M,as applicable.ii)iii)Bend thinning allowance shall be provided for all bends as per therecommendations of ANSI B 31.1.Maximum carbon content for ASTM A 106 Gr. B or A- 105 shall belimited to 0.30% and for ASTM A 106 Gr. C, it shall be limited to0.35%.iv) All drains and vent lines in piping system with design pressure 40kg/cm2 and above shall have two valves in series.v) Wherever mitered bends are used, the thickness of pipe from whichthey are fabricated shall conform to the requirements of IBRRegulations 361 (C). The angle between axes of adjoining pipesections shall not exceed 22.5 degree.vi)vii)Piping system fabrication shall be in accordance with the requirementof ANSI B 31.1. However for system under purview of IBR, therequirements of IBR shall also be complied with.Where welded pipe and fittings are used the longitudinal weld seamsof adjoining sections shall be staggered by 90 degree.18.1.9 Valvesi) All valves shall be full port and shall meet the requirements of ASMEB 16.34. The class of the valves shall be compatible to the servicerequirements. All materials that are bent, forged or formed shall besubject to heat treatment after the forming operations as required bythe original material specification. For alloy steel materials thepreferred heat treatment process is full annealing.ii)Valves of size 65 NB and above shall have butt welded ends as perANSI B16.25 and valves 50 NB and below shall have socket weldends as per ANSI B16.11. Rubber lined valves shall have flanged endsas per ANSI B16.5.177

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Unitsiii)iv)All gate and globe valves shall be with outside screw and yoke withrising stem. Gate valves below 100 NB shall be solid wedge/flexiblewedge type. Valves of class 150/ 300 and size 100 NB and above shallbe of flexible wedge type. However, for sizes 100 mm NB and abovefor temperatures above 300 0 C, parallel slide valves are also acceptable.All globe valves shall be capable of being closed against the designpressure. Where globe valve has been specified for regulationpurpose, the disc shall be tapered plug type and suitable for controllingthroughout its lift.v) All gate and globe valves shall have bonnet-back seating arrangementto facilitate easy replacement of packing with the valves in service.vi)All gate, globe and check valves shall be designed for reconditioningof seating surfaces and replacement of stem and disc without removingthe valve body from the line.vii) Minimum differential hardness between seat and other disc materialshall be 50 HB in case of 13% chrome hardened with heat treatment ofsteel.viii) For all globe and check valves, the direction of flow shall be clearlystamped on the body of the valve.ix)Locking arrangement, where provided shall be of non-detachable type.x) Integrated bypass valves:a) The requirement of integral bypass valves shall be worked out, asper process requirement.b) Integral bypass shall be motor operated if main valve is motoroperated.c) Bypass pipe shall be of seamless construction and thicknesscorresponding to minimum of schedule 80 and shall be of thesame material class as the main pipe.xi)For valves of size 65 NB and above in vacuum service, water glandsealing arrangement shall be provided. Valves of size 50 NB andbelow shall have extra, deep gland packing without requiring watergland sealing.18.1.10 Hangers and supportsi) All hangers and supports shall be so erected that they are preferablyvertical when the piping is in hot condition (rated parameters).However, in piping system connected to the turbine/turbine valvenozzles it may be required to erect the hangers/supports vertical in the178

<strong>Standard</strong> <strong>Technical</strong> <strong>Features</strong> <strong>of</strong> <strong>BTG</strong> <strong>System</strong> <strong>for</strong> <strong>Supercritical</strong> <strong>660</strong>/800 MW Thermal Unitsiii)iv)All gate and globe valves shall be with outside screw and yoke withrising stem. Gate valves below 100 NB shall be solid wedge/flexiblewedge type. Valves <strong>of</strong> class 150/ 300 and size 100 NB and above shallbe <strong>of</strong> flexible wedge type. However, <strong>for</strong> sizes 100 mm NB and above<strong>for</strong> temperatures above 300 0 C, parallel slide valves are also acceptable.All globe valves shall be capable <strong>of</strong> being closed against the designpressure. Where globe valve has been specified <strong>for</strong> regulationpurpose, the disc shall be tapered plug type and suitable <strong>for</strong> controllingthroughout its lift.v) All gate and globe valves shall have bonnet-back seating arrangementto facilitate easy replacement <strong>of</strong> packing with the valves in service.vi)All gate, globe and check valves shall be designed <strong>for</strong> reconditioning<strong>of</strong> seating surfaces and replacement <strong>of</strong> stem and disc without removingthe valve body from the line.vii) Minimum differential hardness between seat and other disc materialshall be 50 HB in case <strong>of</strong> 13% chrome hardened with heat treatment <strong>of</strong>steel.viii) For all globe and check valves, the direction <strong>of</strong> flow shall be clearlystamped on the body <strong>of</strong> the valve.ix)Locking arrangement, where provided shall be <strong>of</strong> non-detachable type.x) Integrated bypass valves:a) The requirement <strong>of</strong> integral bypass valves shall be worked out, asper process requirement.b) Integral bypass shall be motor operated if main valve is motoroperated.c) Bypass pipe shall be <strong>of</strong> seamless construction and thicknesscorresponding to minimum <strong>of</strong> schedule 80 and shall be <strong>of</strong> thesame material class as the main pipe.xi)For valves <strong>of</strong> size 65 NB and above in vacuum service, water glandsealing arrangement shall be provided. Valves <strong>of</strong> size 50 NB andbelow shall have extra, deep gland packing without requiring watergland sealing.18.1.10 Hangers and supportsi) All hangers and supports shall be so erected that they are preferablyvertical when the piping is in hot condition (rated parameters).However, in piping system connected to the turbine/turbine valvenozzles it may be required to erect the hangers/supports vertical in the178

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