1.5.5 Bolts & Nuts :-

Depending upon the Service parameters, various bolting material specified in the piping classes is as follows

- Alloy steel stud Bolts & Nuts

- Stainless steel Bolts & Nuts

- Black carbon steel Bolts & Nuts

1.5.6 Gaskets :-

As per service requirements the gaskets specified are :

- SS Spiral wound gasket with asbestos filler

- SS Spiral wound gasket with carbon filler

- SS Spiral wound gasket with Teflon filler

- Compressed asbestos fiber gaskets (CAF)

- Corrugated Jacketed gaskets with different filler

- Rubber gaskets

- Metallic RTJ gaskets etc.

1.5.7 Strainers :-

- Temporary strainer

- Tee type strainer

- Y type strainer

- Specialities filters

1.5.8 Steam traps :-

- Thermodynamics

- Thermostatic

- Ball float type

1.5.9 Branch Connection :-

- Pipe to pipe branch without Reinforcing pad

- Pipe to pipe branch with Reinforcing pad

1.5.10 Spectacle Blind / Blind and spacer.

- Single piece spectacle blind (upto 10" dia )

- Two piece Spacer and blind ( pipe dia 12" and above)

- Facing to suit raised face, RTJ etc.-

1.5 Small Bore Piping :-

Generally piping upto 11/2" nominal bore is termed as small bore piping and is having socket weld or screwed construction. In very high pressure system (e.g.1500# and 2500# rating) it can be Butt weld construction.

1.6 Large Bore piping :-

Piping systems having 2" and above nominal bore. Upto size 24" is considered as large bore piping.

Above 24" Size. i.e. 26" and above upto any size (114" for RPL project ) is extra large bore piping.

2.0 Materials :-

2.1 Carbon Steel (CS) :-

Carbon steel to various specifications is the most commonly specified material for most of the Process and utility services for pipe and piping components having temperature limits between-290 C upto 4540 C for noncorrosive and corrosive services depending upon the suitability safety and Economy.

2.2 Low Temperature Carbon steel (LTCS) :

Low temperature carbon steel pipe and piping components are specified for service temperature range from -300 C to 450 C

2.3 Alloy Steel (AS) :-

Alloy steel pipe and piping components are specified for high temperature services (above 4540 C)

Commonly specified alloy steel grades depending upon the temperature and services are

- carbon-1/2 molydenum

- 1 1/4 chrome (P11)

- 2 1/4 chrome (P22)

- 5 Chrome (P5)

- 9 chrome (P9)

2.4 Stainless Steel (SS) :-

Application of stainless steel in material selection and material specification in broader concept is as follows.

2.4.1 Corrosive services :-

Where service fluid is corrosive and the use of carbon steel is not acceptable from contamination purity, iron pickup and health hazard and where galvanised piping or non-ferrous piping is also not acceptable in all such cases stainless steel is specified.

2.4.2 High temperature services :-

Where the higher temperature services for which alloy steel cannot be used generally stainless steel of suitable grade (SS304 H grade) is used for temperature above 5600 C / 5850 C.

2.4.3 Cryogenic services :-

For extreme low temperature services, temperature below -1000 C and up to - 2000 C stainless steel material generally specified

2.5 Lined Piping :-

Where the service is corrosive and does not have much temperature. Lined Piping depending upon the economy and effectiveness. Is specified. Various types of lined piping systems are there in the Hydrocarbon industry usage. e.g.

2.5.1 Epoxy lined carbon steel :-

Generally for seawater services of large diameter and long piping runs as it has very low co-efficient of friction.

2.5.2 Rubber lined piping :-

Rubber lined carbon steel piping with flanged piping and fittings is another alternate for services like deminaralised water and other chemicals where economy. Moderate temperature and iron pickup are main consideration.

2.5.3 Cement lined carbon steel :-

Carbon steel piping lined with reinforced cement from inside is also suitable for services like sea water but the co-efficient of friction, length and size of piping system involved may be deciding factors.

2.5.4 Other examples of lined piping are glass lined,teflon lined, polypropylene lined etc.depending upon the type of fluid And its application

2.6 Non-ferrous piping

Non ferrous piping e.g. high-density polyethylene (HDFE) Polyvinyl chloride (PVC) RCC etc. are also specified based on suitability of its application.

2.7 Special materials :-

Special materials in piping system are specified depending upon the criticality of service, temperature, corrosion and abrasion resistance and suitability e.g.

- Inconel

- Incoloy

- Duplex stainless steel

- SS 321 grade

- Monel

- P91 grade alloy steel (high strength. High temperature resistant)

3.0 Basis of material specification / piping classes :-

Various parameter which from the basis of material specifications / piping classes are as flolows

3.1 Pressure :-

Pressure of the piping system ranges from vacuum pressure to very high pressures accordingly. The categorization of piping classes is done based on the pressure ratings

Pressure ratings are normally applicable to flanges. Flanged valves, socket weld fittings and socket weld valves.

3.1.1 Flanges and flanged valve rating:-

These are

- 150# rating

- 300# rating

- 600# rating

- 900# rating

- 1500# rating

- 2500# rating

3.1.2 Socket weld fittings :-

These are normally

- 3000 # rating

- 6000# rating

- 9000# rating

3.1.3 Socket weld valves :-

These are normally 800# rating

3.2 Temperature :-

Wide range of temperature from - 2000 C upto 7500 C from the basis of number of piping classes in preparation of material specification and its suitability.

Accordingly, the different and broader categorisation of piping classes based on temperature and service conditions of system are as follows.

- -290 C to 1000 C

- -290 C to 1500 C

- -290 C to 2600 C

- -290 C to 3990 C

- -290 C to 4270 C

- -290 C to 4540 C

- -290 C to 5380 C

- -290 C to 5500 C

- -290 C to 5660 C

- -290 C to 5930 C

- -290 C to 6500 C

- -290 C to 8000 C etc.

The above temperature ranges depending upon the service fluid. Service requirements are base material e.g. CS. AS. SS. GI. Corrosion requirements etc. from the basis for generation of a suitable piping class.

3.3 Service or fluid :-

Various hydrocarbon and utility service necessitate Specific requirements from material selection point of view to be considered in the piping classes.

Various process and utilities in general are as follows.

3.3.1 Process :-

- Hydrocarbon - non corrosive

- Hydrocarbon - corrosive

- Hydrocarbons with Sulphur

- Hydrocarbons with Hydrogen

- Hydrocarbons with hydrogen and H 2 S

- Hydrocarbon With Sour water NACE

- Caustic (25% and above)

- Caustic - PWHT (less then 20%)

- Hydrogen

- Sulphur

- Amine - (PWHT)

- Sour water - NACE

- Nitrogen

- Catalyst

- Chemicals

- Slops - light. heavy. Cracked

- Hydrochloric acid

- Sulphuric acid

- Blow downs

- Fuel oil

- Fuel gas

- Oils - lube. Seal. Flushing etc.

3.3.2 Utilities :-

- Steam - low. Medium, high pressure.

- Condensate - low, medium, high pressure

- Air - Instrument air, Plant air, breathing air.

- Water - cooling water supply and return

- Water - cooling water (fresh)

cooling water (sea water)

Boiler feed water.

Desalinated Water.

Potable water

Treated water

Process water

Utility water