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CAESAR II, AUTO PIPE ETC.

Caesar II, Auto Pipe etc.

In your system first decide the LOCATION where you want to install the spring. Then remove all NEARBY supports which are not taking load in thermal operating case. Now run the program and the sustained load on that support node is your hot load. The thermal MOVEMENT in that location is your thermal movement for your spring. Now assume variability for your spring. So CALCULATE

Spring constant = (Hot load × variability)/displacement. Now with spring constant and hot load enter any vendor catalog to select spring inside the travel range.

In your system first decide the location where you want to install the spring. Then remove all nearby supports which are not taking load in thermal operating case. Now run the program and the sustained load on that support node is your hot load. The thermal movement in that location is your thermal movement for your spring. Now assume variability for your spring. So calculate

Spring constant = (Hot load × variability)/displacement. Now with spring constant and hot load enter any vendor catalog to select spring inside the travel range.

• Select the height from VENDOR catalog based on SPRING SIZE and stiffness class.
• For BASE mounted variable spring hanger the height is mentioned directly. It is the spring height.
• For top mounted variable spring hanger’s ass spring height with turnbuckle LENGTH, clamp/lug length and rod length.

Major parameters are: Spring TAG, Cold load/Installed load, VERTICAL and horizontal movement, Piping DESIGN temperature, Piping Material, Insulation thickness, Hydro-test load, Line NUMBER etc.

Major parameters are: Spring TAG, Cold load/Installed load, Vertical and horizontal movement, Piping design temperature, Piping Material, Insulation thickness, Hydro-test load, Line number etc.

VARIABILITY= (Hot Load-Cold load)/Hot load = (SPRING Constant × displacement)/Hot load.

LIMIT for variability for variable spring hangers is 25%.

Variability= (Hot Load-Cold load)/Hot load = (Spring Constant × displacement)/Hot load.

Limit for variability for variable spring hangers is 25%.

In CONSTANT Spring hanger the load remains constant THROUGHOUT its travel range. But In variable spring hanger the load VARIES with displacement.

Spring hangers are used when thermal displacements are upwards and piping system is lifted off from the support position. Variable spring hanger is preferable as this is less costly.

Constant springs are used:

1. When thermal displacement exceeds 50 MM
2. When variability exceeds 25%
3. Sometimes when piping is connected to strain sensitive equipment LIKE steam turbines, centrifugal compressors etc and it becomes very difficult to qualify nozzle loads by variable spring hangers, constant spring hangers can be used.

In Constant Spring hanger the load remains constant throughout its travel range. But In variable spring hanger the load varies with displacement.

Spring hangers are used when thermal displacements are upwards and piping system is lifted off from the support position. Variable spring hanger is preferable as this is less costly.

Constant springs are used:

The basic allowable stress is DEFINED in RESPECTIVE code. For example as per B 31.3 the basic allowable stress for a material is the minimum of the following:

1. 1/3rd of tensile strength at design temperature.
2. 2/3rd of yield strength at design temperature.
3. 100% of average stress for a creep rate of 0.01% per 1000 hours.
4. 67% of average stress for rupture at the END of 100000 hours.
5. 80% of minimum stress for ruptures at the end of 100000 hours.
6. For austenitic stainless steel or nickel alloys the lower of yield strength and 90% of yield strength at temperature.
7. For structural grade materials 0.92 TIMES of the lowest value of point (a) to (f)

The basic allowable stress is defined in respective code. For example as per B 31.3 the basic allowable stress for a material is the minimum of the following:

The main differences are listed below:

1. Material allowable stresses are different in both codes.
2. STRESS increases due to occasional loads are different in each CODE.
3. B 31.3 NEGLECTS torsion while calculating sustained stresses, but B 31.1 includes it.
4. Sustained stress CALCULATION is specific in B 31.1 but undefined for B 31.3.
5. B 31.1 INTENSIFIES torsion but B31.3 does not intensify it.

The main differences are listed below:

POWER PIPING: ASME B 31.1

PROCESS Piping: ASME B 31.3

Power Piping: ASME B 31.1

Process Piping: ASME B 31.3

AMERICAN SOCIETY for MECHANICAL ENGINEERS.

American Society for Mechanical Engineers.

Hand-lever, hand-wheel, CHAIN OPERATOR, GEAR operator ETC.

Hand-lever, hand-wheel, chain operator, gear operator etc.

Shell-hydrostatic, seat-hydrostatic, seat-pneumatic

Shell-hydrostatic, seat-hydrostatic, seat-pneumatic

Valve in which the closing OPERATION of valve is achieved by 90 degrees turn of the closing ELEMENT.

Valve in which the closing operation of valve is achieved by 90 degrees turn of the closing element.

This TERM is USED to indicate the premature erosion of the valve SEAT caused by excessive velocity between seat and seat disc, when valve is not CLOSED tightly.

This term is used to indicate the premature erosion of the valve seat caused by excessive velocity between seat and seat disc, when valve is not closed tightly.

All parts that come in contact with SURFACE FLUID are CALLED wetted parts.

All parts that come in contact with surface fluid are called wetted parts.

API 600.

API 600.

Trim is composed of stem, seat SURFACES, back seat BUSHING and other small internal parts that normally CONTACT the surface fluid.

Trim is composed of stem, seat surfaces, back seat bushing and other small internal parts that normally contact the surface fluid.

Cast IRON, BRONZE, gun METAL, carbon steel, stainless steel, ALLOY carbon steel, polypropylene and other PLASTICS, special alloys.

Cast iron, bronze, gun metal, carbon steel, stainless steel, alloy carbon steel, polypropylene and other plastics, special alloys.

Multi-port, FLUSH bottom, FLOAT, foot, pressure RELIEF, BREATHER.

Multi-port, flush bottom, float, foot, pressure relief, breather.

CHECK VALVE.

check valve.

Globe, needle, BUTTERFLY, DIAPHRAGM, piston, punch.

Globe, needle, butterfly, diaphragm, piston, punch.

Gate, BALL, plug, piston, DIAPHRAGM, butterfly, PINCH.

Gate, ball, plug, piston, diaphragm, butterfly, pinch.

ISOLATION, REGULATION, non-return and SPECIAL PURPOSES.

Isolation, regulation, non-return and special purposes.

MUST be LOCATED at the BOTTOM SECTION of DRUM.

Must be located at the bottom section of drum.