4 General Technical Specification of Bhilai Steel Plant, SAIL ...

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General Technical Specification
of the respective State prior to manufacture. All welding procedures, stress
relieving procedures, inspection / testing / certificates and all other records shall
have to be approved by Chief Inspector of Boilers in approved form.
Pipes having nominal bore less than 15 mm, shall not be used. Design pressure of
steam and all other service pipelines shall be considered as 1.2 times the
maximum expected pressure. However it shall not be less than 4.0 kg/cm 2 gauge
for steam services and 3.5 kg/cm 2 gauge for other services.
Design temperature for steam services shall be as pr IBR and for other pipelines
shall be 5 deg. above the maximum sustained service temperature expected.
All the piping coming under the purview of IBR, shall be designed with the
allowable design stresses as per IBR. For all other piping, the allowable design
stress shall not be more than that specified in ANSI B 31.1 or BS:806 latest
revision. Pipe thickness of all pipeline shall be taken as per the pipe thickness
schedules. The design and stress analysis shall take into account the effect of
internal/external pressures, thermal expansion, self weight of piping, support
reactions, shock due to relieving devices, surge and water hammer, earth quake
and wind effect, noise and vibrations, corrosion and erosion etc. and any other
effects dictated by recommended engineering practices.
Adequate flexibility shall be provided in the pipelines to keep stress and reactions
in the system arising due to thermal expansion or other effects within limits. Where
the piping terminates at an equipment or at the terminal point of a system, the
reactions and thermal movement imposed by piping on the equipment or the
system concerned shall be well within the limits specified.
The flexibility analysis of steam, condensate and hot service media pipelines shall
be furnished.
01. Pipes shall be sized for minimum pressure drops and considering the velocity limitation
for various types of fluids.
02. Adequate flexibility shall be provided in the pipelines to keep stresses and reactions in
the system arising due to thermal expansion or other effects within limits. Where the
piping terminates at an equipment or at the terminal point of a system, the reactions and
thermal movement imposed by piping on the equipment or the system concerned shall
be well within the limits specified.
03. If cold springing of pipeline is used, care shall be taken in determining the location and
amount of cold spring gap. Cold spring gap shall be located at points where the bending
and torsional moments are minimum. Use of cold spring gaps less than 10mm shall not
be acceptable and cold spring gaps above 100mm shall be avoided. All outdoor piping
exposed to sunlight carrying fluid at a temperature less than 80 0 C shall be designed
considering thermal expansion corresponding to 80 0 C and empty pipe as one of the
operating conditions although not necessarily the worst.
04. All piping shall have butt welded connections with minimum of flanged joints for
connection to vessels and equipment to facilitate erection and maintenance. All high
pressure steam valves and accessories shall have welded connections. Standard fittings
shall be used wherever practicable. Unless otherwise specified, for all welded lines with
pressure above 4 kg/cm2 g and / or temperature above 200 0 C, branch connections with
branch sizes upto 25% of welded mains shall be made with special forged steel welded
fittings.
Gases & Liquid Fluids
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GS-02