1.5.1 Purpose of the classes of piping systemsPiping systems are subdivided into three classes, denoted as class I, class II and class III, for the purpose of acceptance of materials, selection of joints, heat treatment, welding, pressure testing and the certification of fittings.
1.5.2 Definitions of the
classes of piping systems
|Media conveyed by the piping system||Class I||Class II (1) (4)||Class III (7)|
|Toxic media||without special safeguards (3)||with special safeguards (3)||not applicable|
|Corrosive media||without special safeguards (3)||not applicable||not applicable|
|Flammable media:||without special safeguards (3)||with special safeguards (3)||not applicable|
|Oxyacetylene||irrespective of p||not applicable||not applicable|
|Steam||p > 1,6 or T > 300||other (2)||p <= 0,7 and T <= 170|
|Thermal oil||p > 1,6 or T > 300||other (2)||p <= 0,7 and T <= 150|
|Fuel oil (8)|
Flammable hydraulic oil (5)
|p > 1,6 or T > 150||other (2)||p <= 0,7 and T <= 60|
|Other media (5) (6)||p > 4 or T > 300||other (2)||p <= 1,6 and T <= 200|
(1) Valves under static pressure on oil fuel tanks or lubricating oil tanks belong to class II.
(2) Pressure and temperature conditions other than those required for class I and class III.
(3) Safeguards for reducing leakage possibility and limiting its consequences:
e.g. pipes led in positions where leakage of internal fluids will not cause a potential hazard or damage to surrounding areas which may include the use of pipe ducts, shielding, screening etc.
(4) Valves and fittings fitted on the ship side and collision bulkhead belong to class II. See also [20.4.3] b).
(5) Steering gear hydraulic piping system belongs to class I irrespective of p and T.
(6) Including water, air, gases, non-flammable hydraulic oil.
(7) The open ended pipes, irrespecitve of T, generally belong to class III (as drains, overflows, vents, exhaust gas lines, boiler escape pipes, etc).
(8) Design pressure for fuel oil systems is to be determined in accordance with Tab 4.
Note 1 : p : Design pressure, as defined in [1.3.2], in MPa.
Note 2 : T : Design temperature, as defined in [1.3.3], in °C.
Note 3 : Flammable media generally include the flammable liquids as oil fuel, lubricating oil, thermal oil and flammable hydraulic oil
|Working pressure P, in bar||Working temperature T, in °C|
|T <= 60||T > 60|
|P <= 7||3 bar or max. working pressure, whichever is the greater||3 bar or max. working pressure, whichever is the greater|
|P > 7||max. working pressure||14 bar or max. working pressure, whichever is the greater|