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

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General Technical Specification
rope supports may be considered. In exceptional cases where distance exceeds the
limiting span, suitable stiffening of pipe section to prevent sagging may be considered.
At sliding supports pipe saddle shall be allowed to rest on bearing plate for free
movement. In case U-clamps are provided, clearance shall be maintained for pipe
movement by providing two nuts on opposite sides.
All intermediate supports shall be of sliding type. Anchor supports shall be located based
on piping configuration and layout to provide adequate flexibility.
Distance between two consecutive fixed supports in straight runs of pipe route should be
approx 70 m. However, in special cases it may go up-to 100 m (max.). In no case it
should exceed 100 m.
However, for steam pipeline it should be limited to 60 m. For pipe dia. above 100 mm
cold pull if any during erection may be given as per instructions of the respective
drawings.
To reduce friction force transmitted to supports, roller supports or anti friction pad
supports can also be used.
02.21 FLEXIBILITY ANALYSIS
Piping arrangement shall provide for flexibility of lines to take care of the thermal
expansion, contraction and equipment settlement. Large reactions or moments at
equipment connections shall be avoided . Expansion computation shall be made on the
basis of a base temperature of 21.1deg C (70 deg F) and shall cover ( +ve, or –ve )
design temperature(s) as given.
i) Flexibility analysis shall meet the requirement of Code ASME B-31.3 (Latest
Edition). Analysis shall consider stress intensification factors as per ASME
B31.3.
ii) Lines which shall be subjected to steam out conditions, shall be designed and
analyzed at low –pressure steam design temperature of line whichever is more.
Lines having negative design temperature shall be analyzed for both conditions
separately.
iii) Flexibility Analysis of lines shall be carried out using simplified methods or a
comprehensive computer program. Comprehensive computer analysis shall be
carried out for the piping for lines connected to equipment like vessels, pumps,
filters, furnace, compressors or other strain sensitive equipment. The result of
the analysis must satisfy the allowable loading on the nozzles of such
equipment.
iv) Piping shall be adequately supported for the weight of piping, water, attached
unsupported components, wind, seismic, insulation and any other applicable
forces. Care should be taken that these supports are adequate to prevent
excessive stress, load or moments in either the piping or terminal nozzles of the
equipment to which it is connected. Adequacy of supporting of lines having
heavy valves shall be checked. The support shall be indicated in the piping
General Arrangement Drawings and Isometrics as applicable.
v) Safety valve manifolds and downstream of control valves shall be adequately
supported to avoid vibrations.
Gases & Liquid Fluids
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GS-02