Section 5(5) in The Petroleum and Natural Gas Regulatory Board (Determining Capacity of Petroleum, Petroleum Products and Natural Gas Pipeline) Regulations, 2010
(5)The methodology for calculation of pipeline capacity shall be as under:(a)Natural Gas Pipelines: - (i) The entire pipeline system shall be configured in the selected software package operating offline. The steady state condition of the pipeline hydraulics with contractual flow parameters (pressure, temperature and flow) at entry and exit points shall be simulated in the selected software package.(ii)At the originating point and at intermediate points in the direction of flow, set the pressure as a fixed parameter corresponding to the maximum allowable operating pressure (MAOP) or available compression facilities and compute the maximum pressure at all exit points with contractual flow.(iii)Thereafter, assuming gas at the entry point (single source of gas) is unlimited, the selected software will be run till any customer connected to the system reaches limiting condition of pressure required at the respective exit point or maximum flow capacity is reached at entry or intermediate compressor stations (if installed in the system) or the velocity of natural gas reaches limiting value as defined in these regulations. The capacity at this juncture would be the maximum system capacity achievable in the pipeline system and the customer at the exit point where pressure becomes limiting shall be the critical customer.(iv)Now simulate the flow from any other source considering the entry should take place at the pressure marginally higher than the available at that section. The exercise carried above shall be repeated to get threshold pressure limit at any location to calculate the flow exiting from each point in the entire pipeline system and the sum total of these flows shall be the pipeline capacity as determine by the approved flow equation and selected software. This would be the system capacity for multi source pipeline system.(v)The section wise capacity of the pipeline system shall be computed between an entry point and exit points. In case of multi entry, the section wise capacity may also be determined taking into account flow from each of the input points. Thus the first section is from first entry point to first exit point and second section shall be from first entry point to second exit point and another section and so on. This exercise shall be repeated for each of the entry point. However, in a real time working, the effect of each source will have to be workout on the pipeline capacity and the flow parameters at intermediate points shall not be allowed to reduce the system or section capacity. The procedure mentioned above shall be applicable for determining the capacity of specific section of the pipeline.(vi)In a real time model of pipeline system, the flow at specific entry point shall be the actual available flow from that source. The gas supply from various sources at entry points and delivery at exit points shall be scheduled to optimize the pipeline system capacity.(vii)The obligatory or contractual requirement of pressure at any exit point shall determine the possible capacity within a particular section serving that exit points. Provided further that maintainability of a particular steady state hydraulics condition at any exit point shall be mutually determined between capacity determining authority and the transporter within the flexibility available in the system. The section wise capacity thus calculated with single or multiple entry and exit points shall be run with the approved flow equation and selected software package offline in the steady state operation of the system to arrive at capacities of various sections.(viii)This exercise shall be continued for computing section wise capacity of the pipeline system including the spur lines. In case of spur lines the tap off point shall be designated as the source point or entry point for spur line and computable (to be fed to the flow computing formula) or contractual hydraulics shall be allowable pressure at that point after accounting for the pressure drop from the tap off point to the consumer point of the spur line or branch line.(ix)For determining, de-rated MAOP of an existing pipeline, results based on the Instrumented pig survey shall be considered to calculate de-rating factor. In absence of results of the intelligent pig survey (IPS) in any pipeline, hydro testing shall be carried out to establish MAOP of that pipeline, as per provisions in the relevant regulations on Technical Standard and Specifications including Safety Standards. Provided that in absence of hydro testing the entity may put up proposal for de-rating based on random thickness survey of the pipeline. Board reserves the right to check such survey data.(x)The entity shall submit the details of maximum achievable system capacity and section wise capacity of the natural gas pipeline so determined, under the steady state simulation with the details of variable or constant parameters, to the Board in the specified format at Schedule A along with the hydraulic gradient and system flow diagram for the pipeline system including compressor stations, metering and regulating stations as applicable.(b)Petroleum Product Pipelines: - (i) In a multi product pipeline, the maximum achievable capacity shall be determined based on the characteristics of High Speed Diesel (HSD) whereas for pipelines dedicated for transportation of single product like LPG, Naphtha or ATF etc, characteristics of that product only shall be considered.(ii)The entire pipeline system shall be configured in the selected software package operating offline. The steady state of hydraulics of the pipeline shall be entered into the system.(iii)At the originating point and at intermediate points in the direction of flow set the pressure as a fixed parameter corresponding to maximum allowable operating pressure (MAOP) or pumping facilities available at these locations, as the case may be, and compute the maximum possible flow in the pipeline system. This shall be the capacity of the pipeline system under prevailing, facilities and conditions.(iv)Thereafter, assuming products at the entry points as unlimited, the Station Discharge Head (SDH) at the pump station equal to Maximum Allowable Operating Pressure (MAOP) of the pipeline, the entire pipeline system shall be configured in the selected software package operating offline. The steady state of hydraulics of the pipeline shall be entered into the system for computing the maximum achievable flow in the pipeline system using the selected software and approved flow equation.(v)At the first and subsequent withdrawal points in the direction of flow getting the required pressure or SDH as a fixed parameter, the maximum, possible flow within that section shall be computed based on, the methodology specified above. Similarly, the possible volume flow shall-be calculated from, section to section and tabulated up to the last exit point taking into account, the quantity available from other injection points.(vi)If the capacity of a Pipeline have been downgraded or decreased due to de-rating of the MAOP of the pipeline due to factors like metal loss, the de-rated capacity of such pipelines shall be determined considering results of Instrumented pig survey. In the absence of results of IPS in any pipeline, hydro testing shall be carried out to establish MAOP of that pipeline as per provisions in the relevant regulations on Technical Standard and Specifications including Safety Standards. Provided that in absence of hydro testing the entity may put up proposal for de-rating based on random thickness survey of the pipeline. Board reserves the right to check such survey data.(vii)The requirement of a pressure or SDH at any exit point shall determine the possible capacity within a particular section serving that exit points. Provided further that maintainability of a particular hydraulics condition at any exit point shall be mutually determined between capacity determining authority and the transporter within the flexibility available in the system. The section wise capacity thus calculated with single or multiple entry and exit points shall be run with the selected software package offline in the steady state operation of the system to arrive at capacities of various sections.(viii)The entity shall submit the maximum achievable pipeline capacity as well as section wise capacity of the product pipeline so determined, under the steady state simulation with the details of variable or constant parameters, to the Board in the specified format at Schedule B along with the hydraulic gradient and system flow diagram for the pipeline system.(c)In case the contractual pressure at any entry and exit point is within a band, the arithmetic mean rounded upto first decimal point shall be considered.(d)The annual capacity of pipeline system and sections shall be as per the operation days specified in the Access Code for respective system.
