TOTAL CAABILITIES IN THE IELINE INDUSTRY UTILITY TECHNOLOGIES INTERNATIONAL CORORATION Cincinnati Columbus West Jefferson
COMMON NATURAL GAS ENGINEERING ROBLEMS OGA SEMINAR DECEMBER 3, 2012
RELIEF VALVE SIZING GUIDELINES UROSE RULES RESSURE LIMITATIONS REGULATOR MAXIMUM CAACITY RELIEF VALVE CAACITY RELIEF VALVE VENT IINE SIZING OGA Seminar 2012 2
RELIEF VALVE SIZING GUIDELINES UROSE rotection against accidental over pressuring of a pipeline OGA Seminar 2012 3
RELIEF VALVE SIZING GUIDELINES 192.195 rotection against accidental over pressuring 192.199 Requirements for design of pressure relief and limiting devices 192.201 Required capacity of pressure relieving and limiting stations 192.739 Inspection and testing 192.743 Capacity of relief devises. OGA Seminar 2012 4
RELIEF VALVE SIZING GUIDELINES Rules of pressure limitations MAO 60psi... MAO +10% (or 75% SMYS) which ever is less MAO 12psi < 60psi... MAO + 6psi MAO < 12psi... MAO + 50% L prevent unsafe operation of any appliance OGA Seminar 2012 5
RELIEF VALVE SIZING GUIDELINES RESSURE LIMITATIONS MAO MAO+ Allowable over-pressure build-up System ressure Normal Operation MAO MAO+ Allowable over-pressure build-up System ressure Accidental Operation OGA Seminar 2012 6
RELIEF VALVE SIZING GUIDELINES REGULATOR MAXIMUM CAACITY The regulator capacity to be vented is maximum capacity based on the maximum inlet pressure (upstream MAO) and maximum outlet pressure Assume that no flow is going into the downstream system OGA Seminar 2012 7
RELIEF VALVE SIZING GUIDELINES RELIEF VALVE CAACITY In sizing relief valves assume that no flow is going into the downstream system Relief valves are sized using: othe manufacturer's Capacity tables o The manufacturer's Flow coefficients for relief valve sizing othe manufacturer's Sizing equations OGA Seminar 2012 8
RELIEF VALVE SIZING GUIDELINES RELIEF VALVE CAACITY Required pressure buildup from set point SET OINT OGA Seminar 2012 9
RELIEF VALVE SIZING GUIDELINES Inlet piping Keep it as short as possible Same size as the relief valve inlet A full port shut-off valve Vent piping Keep it as short as possible Same size as the relief valve outlet or larger Double the size if longer than 10 feet or Use vent line sizing equations NOTE: If relief valve is located inside a building o vent to the outside 10
RELIEF VALVE SIZING Example Relief Valve Sizing roblem - Annual Verification Existing system consists of a single regulator and a relief valve. The system has a volumetric requirement of 2.3 MSCFH. You are responsible for the annual capacity verification of the relief valve. roblem 1: erform the annual capacity calculation. 1) Is regulator capacity adequate? 2) Is relief valve capacity adequate? 3) Correct any discrepancies OGA Seminar 2012 11
RELIEF VALVE SIZING Example Determine system parameters a. Upstream MAO b. Downstream MAO c. Downstream maximum operating pressure d. Regulator maximum capacity 1) Use the maximum inlet pressure: That is the MAO 2) Determine the set point of the relief valve e. Determine the pressure that will produce the set point plus the allowable maximum pressure build-up f. Verify relief valve capacity at the stated conditions g. Compare the maximum capacity of the regulator to the capacity of the relief valve h. Verify that the capacity of the relief valve is greater than that of the regulator. OGA Seminar 2012 12
RELIEF VALVE SIZING Example Calculate the maximum capacity of the regulator Select from the 1 Fisher 627 bulletin the 1/4 orifice flow coefficient C g = 50 & C 1 =29.3 OGA Seminar 2012 13
REGULATOR SIZING Regulator Capacity Calculation use the Universal Sizing Equation Non-Critical (sub sonic) Flow Inlet Outlet 1.814 Q = 1 S g C g Inlet 3417 sin C1 Inlet Inlet Outlet deg Critical (sonic) Flow Inlet Outlet 1.814 Q = 1.291 C g Inlet OGA Seminar 2012 14
REGULATOR SIZING Regulator Capacity Calculation Determine if in/ out > than 1.814 25 14.48 5 14.48 2.02 Calculate regulator capacity use Equation: Q = 1.291 C g Inlet Q = 1.29 x 50 x 39.48 Q = 2,546.4 Cu Ft/hr Determine relief valve capacity at 7.5 psig set point Determine MAO lus Allowable build-up =15 + 6 Maximum pressure build up at full relief = 21 psig OGA Seminar 2012 16
RESSURE SIG RELIEF VALVE SIZING Relief Valve Capacity Calculation Determine relief valve capacity using the Fisher 1805 relief valve Figure 3. Capacity Curves FLOW MSCFH OGA Seminar 2012 17
RELIEF VALVE SIZING Example OGA Seminar 2012 18
RELIEF VALVE SIZING Example OGA Seminar 2012 19
RELIEF VALVE SIZING Example Compare the capacity of the regulator to the capacity of the relief valve Regulator capacity Q= 2.546 MSCFH Relief Valve capacity from curves Q = 5.3 MSCFH The capacity of the relief valve is greater than that of the regulator therefore we have adequate capacity for overpressure protection of the downstream system OGA Seminar 2012 20
RELIEF VALVE SIZING Solution From the relief valve chart we determine the pressure build up at the failed regulator capacity is 17.5 psi The maximum downstream pressure can build up to 21 psig (15 +6) The17.5 psig pressure build up is less than the 21 psig allowed
RELIEF VALVE SIZING roblem 2: Relief Valve Sizing roblem - Annual Verification Existing system consists of a single regulator and a relief valve. The system has a volumetric requirement of 30 MSCFH. You are responsible for the annual capacity verification of the relief valve. What is max pressure at full relief? 45-60 sig 10-15 sig 60 MAO 1 Mooney Flowgrid 15 MAO 1) Is regulator capacity adequate? 2) Is relief valve capacity adequate? 3) Correct any problems and specify any new equipment that maybe necessary. OGA Seminar Dec 3, 2012 23
RELIEF VALVE SIZING (Solution) roblem 2: Relief Valve Sizing roblem - Annual Verification Existing system consists of a single regulator and a relief valve. The system has a volumetric requirement of 30 MSCFH. You are responsible for the annual capacity verification of the relief valve. 20 sig What is max pressure at full relief 21 sig 45-60 sig 10-15 sig 60 MAO 1 Mooney Flowgrid 15 MAO 1) Is regulator capacity adequate? 2) Is relief valve capacity adequate? 3) Correct any problems and specify any new equipment that maybe necessary. OGA Seminar Dec 3, 2012 24
RELIEF VALVE SIZING System arameters Set up system parameters: MAOs Operating ressures Regulator Set oint? sig What is max allowed pressure at full relief? 45-60 sig 10-15 sig 60 MAO 15 MAO Select from the 1 Mooney Flowgrid flow coefficient table C g = 450 & C 1 =34 OGA Seminar Dec 3, 2012 25
RELIEF VALVE SIZING (Solution) System arameters Set up system parameters: MAOs Operating ressures Regulator Set oint 20 sig What is max allowed pressure at full relief? 45-60 sig 10-15 sig 60 MAO 15 MAO Select from the 1 Mooney Flowgrid flow coefficient table C g = 450 & C 1 =34 OGA Seminar Dec 3, 2012 26
RELIEF VALVE SIZING Flow Equations (Determine which equation to use) Use the Universal Sizing Equation Non-Critical (sub sonic) Flow Inlet Outlet 1.814 Q = 1 S g C g Inlet 3417 sin C1 Inlet Inlet Outlet deg Critical (sonic) Flow Inlet Outlet 1.814 Q = 1.291 C g Inlet OGA Seminar Dec 3, 2012 27
RELIEF VALVE SIZING (Solution) Flow Equations Use the Universal Sizing Equation Non-Critical (sub sonic) Flow Inlet Outlet 1.814 in = (60+14.48) = 2.5 > 1.814 out = (15+14.48) Q = 1 S g C g Inlet 3417 sin C1 Inlet Inlet Outlet deg Critical (sonic) Flow Inlet Outlet 1.814 Q = 1.291 C g Inlet USE THIS EQUATION OGA Seminar Dec 3, 2012 28
Reference materials (Solution) 1 Mooney FlowGrid ressure Regulator 2 Mooney FlowGrid Relief Valve OGA Seminar Dec 3, 2012 29
RELIEF VALVE SIZING (Solution) Regulator Capacity Calculation for relief sizing Determine if in/ out > than 1.814 60 14.48 15 14.48 2.5 Calculate regulator capacity use Equation: Q = 1.291 C g Inlet Q = 1.29 x 450/1000 x 74.48 Q = 43.2 MSCFH Determine relief valve capacity of a 2 Mooney Flowgrid at maximum pressure of 21 psig OGA Seminar Dec 3, 2012 30
RELIEF VALVE SIZING (Solution) Relief valve Capacity Calculation Determine if in/ out > than 1.814 20 14.48 2.38 14.48 Calculate regulator capacity of a 2 Mooney Relief valve Equation: Q = 1.291 C g Inlet Q = 1.29 x 1130/1000 x 34.48 Q = 50.3 MSCFH 50.3 MSCFH is the max capacity of the relief valve at 20 psig set point Note: The Mooney pilot only requires a pressure build up of only 0.5 psig above set point for max capacity OGA Seminar Dec 3, 2012 31
RELIEF VALVE SIZING (Solution) Relief Valve Capacity Verification Compare the capacity of the regulator to the capacity of the relief valve Regulator capacity Q= 43.2 MSCFH Relief Valve capacity from curves Q = 50.3 MSCFH The capacity of the relief valve is greater than that of the regulator therefore we have adequate capacity for overpressure protection of the downstream system OGA Seminar Dec 3, 2012 32