As per ASME-American Standard Mechanical Engineering
B13-3, Chapter 6, High pressure piping system have 10 parts
design of high pressure component
service requirements for piping component
service requirements for piping joints
for piping component
assembly and erection
examination and testing
Applicability for piping designated by the owner as
being in high pressure fluid service. Its requirement are to be applied in full
to piping so designated. High pressure is considered to be pressure in excess of
that allowed by the ASME B16.5 PN 420 rating for the specific design
temperature and material group.
Instrumented Piping: Instrumented piping within the
scope of high pressure piping involves, sealed fluid filled tubing system, with
instruments as temperature orb pressure responsibility devices, control piping
for air, hydraulically.
capacity of the pressure relieving services shall be sufficient to prevent the
pressure from rising more than 10%above the pipe pressure at the operating
temperature during the reliving condition for the single reliving device or
more than 16% above the design pressure more than one device is provide except
as a provided in 3 below.
protection must include one relief device set at or below the design pressure
at the operating temperature for the reliving condition with one device set to
operate a pressure greater than 105% of the device pressure provided 3 below.
pressure reliving device provide for protection against over pressure due to
fire or other unexpected source of external heat shall be set to operate
pressure not greater than 110% of the design pressure of the piping system and
shall be capable the liming the maximum pressure during relief no more than
121% of the design pressure.
The allowable stress is provided in appendix Table K-1 which
is equal to two third of the material yield strength. For solution heat treated
austenite SS and certain nickel alloys with similar stress-strain behaviour,
the minimum of two-thirds the specified minimum yield strength and 90 percent
of the yield strength at temp is used. Similar to base code, this is because
the material has significant strength beyond the nominal 0.2 percent offset
As in the base code, materials
may be used above the maximum temperature foe which allowable stresses are
provided. The temperature must be below that at which creep properties would
govern the allowable stress that would be determined using the base Code
allowable stress criteria.
materials may be used provide the conform to published specification covering
chemistry, physical and mechanical properties. Method and process of
manufacture, heat treatment and quality controls and otherwise meet requirement
of chapter IX.
The impact test requirements are a
very important part of the materials requirements in chapter IX for the high
pressure piping. Essentially all high pressure piping materials and welds must
be impact-tested to determine that they have enough notch toughness for any
temperature condition at which stresses exceed 41 MPa (6 psi).transverse
specimens are required, unless the component size or shape does not permit
cutting transverse specimens.in that case, longitudinal specimens may be used.
However the required impact energy absorption is higher.
For the materials, at least one set
of impact tests per lot is required.
For the impact tests on welds,
significantly more testing is required than in the base code.
For test on welds, separate tests
are not required for each lot of material. Test specimens for the welds and
heat affected ones are required.
The minimum permissible temperature
for a material is the minimum temperature at which an impact test that
satisfies the code requirements was performed. The only exception to this is
the 41-MPa exemption, but that exemption may only be used down to -46°C.Impact
testing, regardless of stress, is required for use at temperatures below that