API 570 (& B31.3) Piping Classification, Intervals, and Categories
What Class is tank farm piping?
Class 3.
For Class 1, 2, and 3 piping, the period between thickness measurements for CMLs or circuits should not exceed
one-half the remaining life.
Inspection of Class 3 and Class 4 secondary SBP is
optional at the owner-users discretion depending upon reliability and risk.
Inspection ISOs are recommended for Class 2 (or appropriate RBI consequence) rack piping with CMLs, except
that grid type drawings may be used if all other details are shown.
Category D Fluid Service is a fluid service in which what applies
(1) fluid is nonflammable, nontoxic, and not damaging to human tissues.
The design gage pressure of Category D fluid service does not exceed
1,035 kPa (150 psi)
The design temperature of Category D fluid service is not greater than
186°C (366°F)
What percentage of CUI and NDE of damaged and undamaged areas for Class 3?
25% of damaged areas and 10% at areas without damage.
On-site hydrocarbons that will not significantly vaporize during release are Class
3
Lube oil and seal oil are in Class
4.
Most utility services are in Class
4.
Fluids that can rapidly vaporize are those with atmospheric boiling temperatures below
50 °F (10 °C) or where the atmospheric boiling point is below the operating temperature.
What percentage of CUI and NDE of damaged and undamaged areas for Class 2?
50% of damaged areas and 33% at areas without damage.
What percentage of CUI and NDE of damaged and undamaged areas for Class 1?
75% of damaged areas and 50% at areas without damage.
Class 1-3 fall under what ASME B31.3 Category for fluid service.
ASME B31.3 Category M
ASME B31.3, Category ? fluid services are equivalent to Class 4
ASME B31.3, Category D Services.
RT or insulation removal and visual inspection is normally required for
CUI inspection at damaged or suspect locations.
Flammable services operating above their auto-ignition temperature are considered what Class?
Class 1 piping.
Piping over or adjacent to water and piping over public throughways are automatically what Class?
Class 1 piping.
On-site hydrogen, fuel gas, and natural gas are all Class
Class 2 piping.
On-site hydrocarbons that will slowly vaporize during release such as those operating below the boiling point but above the flash point are what Class of piping?
Class 2.
On-site strong acids and caustics are part of what Class of piping?
Class 2.
Services not included in other Classes are
Class 2.
Lower risk hydrocarbon piping that does not fall in Class 1, 2, or 4 are considered
Class 3 piping.
Off-site hydrogen, fuel gas and natural gas are Class
Class 3 piping.
Off-site acids and caustics are in what Class?
Class 3.
Off-site distillate and product lines to and from storage and loading are considered what Class?
Class 3.
Services that are potentially harmful to human tissue but are located in remote areas may be included in which class?
Class 3.
Air, nitrogen, and water (including boiler feed water or stripped sour water) are all Part of what Class?
Class 4 piping.
Steam and steam condensate are considered Class
Class 4 piping.
Anhydrous hydrogen chloride is an example of what Class?
Example of Class 1 piping.
Flammable services that can auto-refrigerate and lead to brittle fracture are what Class?
Example of Class 1 piping.
Hydrofluoric acid is an example of what Class?
Example of Class 1 piping.
Hydrogen sulfide (greater than 3 % weight) in a gaseous stream is considered what Class?
Example of Class 1 piping.
Pressurized services that can rapidly vaporize during release, creating vapors that can collect and form an explosive mixture, such as C2, C3, and C4 streams are what Class?
Example of Class 1 piping.
Interval for Class 4
Optional for thickness and Optional for external VT.
What percentage of CUI and NDE of damaged and undamaged areas for Class 4?
Optional.
If inspection of the damaged or suspect areas has located significant CUI, additional areas should be inspected and up to what Max percentage should be inspected?
Up to 100% of the circuit should be inspected.
On-site ambient temperature gasoline is Class 2 because it is below the boiling point but above its flash point, however, what would make it Class 1?
above 550 °F, gasoline should be Class 1 since auto-ignition can occur.
Inspection ISOs are recommended for
all unit piping and all Class 1 (or high consequence RBI) pipe rack piping on which CMLs have been identified for thickness measurement.
Class 1 Services are piping with the highest potential of resulting in
an immediate emergency if a leak were to occur.
Operating temperature of hydrocarbon piping systems should be considered when
assigning piping service class.
For Class 1 and Class 2 piping systems, insert patch welds shall
be 100 % radiographed or ultrasonically tested using NDE procedures that are approved by the inspector.
The operating temperature of a hydrocarbon stream relative to its flash point, boiling point and auto-ignition temperature is a significant factor in
defining potential consequence of a release.
Services that are either flammable but do not significantly vaporize when they leak or flammable but are located in remote areas are in what Class?
in Class 3.
Services that are essentially nonflammable and nontoxic are
in Class 4.
Interval for StA
no regulation on thickness measurements, external VT by class, and 6 months for grade side of interface.
Interval for Class 1
on-half life or Five years for thickness and five years for external VT, < 4 years left -Full remaining life up to 2 years
Interval for Class 3
on-half life or Ten years for thickness and Ten years for external VT, < 4 years left -Full remaining life up to 2 years.
Interval for Class 2
on-half life or Ten years for thickness and five years for external VT, < 4 years left -Full remaining life up to 2 years.
Inspection of Class 4 piping is
optional.
Class 4 piping also includes
plumbing and sewers.
B31.3 does not cover what piping
pressures less than 105 kPa (15 psi).
SBP that is secondary process piping has different minimum requirements depending upon
service classification.
Class 1 and 2 secondary SBP shall be inspected to
the same requirements as primary process piping.
Owner/users shall maintain a record of process piping fluids handled, including
their classifications.
Interval for injection Points
three years for thickness and By class for external VT.
Piping systems that are known to have a remaining life of over 10 years or that are adequately protected against external corrosion do not need
to include NDE in inspections.
Inspection ISOs do not need to be drawn to scale or show dimensions unless necessary
to locate CMLs.
What are some examples for piping not covered in B31.3
tubes, tube headers, crossovers, and manifolds of fired heaters that are internal to the heater enclosure.
Class 2 includes the majority of
unit process piping and selected off-site piping.
