Pressure Retaining Engineering Services

Pressure Piping and Vessels

Rig Engineering Assessment


A. ASME B31.3 Process Piping
– Chapter II Design (for ordinary service piping)
– Chapter IX High Pressure Piping
– Straight pipe and pipe bends design check
– Software: Mathcad calculators prepared by RE

B. ASME Boiler & Pressure Vessel Code, Section VIII Division 1
– Air Pressure Vessel (APV) and Mud Gas Separator (MGS) vessel types and Bulk Tanks
– Software: Codeware Compress

C. DNV Accepted Equivalent von Mises Stress Theory
– Design reference: DNV-OS-E101 Drilling Plant, DNV-RPD101 Structural Analysis of Piping System
– Equivalent von Mises Stress Theory
– Software: Mathcad calculators prepared by RE


A. Recommended Practice DNV-RP-F101 Corroded Pipelines (for cylinders)
– Part A – Load Resistance Factor Design (LRFD). Advanced analysis reflecting probabilistic approach (partial safety factors): safety class level, inspection method, confidence level, standard deviation calculation
– Part B – Allowable Stress Design (ASD). Simple analysis with a global usage factor
– Assessment scope: carbon steel not exceeding API X80 grade, no cyclic loads and sharp defects (cracks), thickness not more than 40 mm, not recommended when fracture is likely to occur
– Software: Mathcad calculators prepared by RE

B. Recommended Practice API 579-1/ASME Fitness-For-Service-1 (for heads and cylinders)
– Part 4 – Assessment of General Metal Loss
– Assessment scope: pipelines and vessels designed in accordance with ASME B31 and BPVC Sec. VIII Div. 1, corrosion loss only
– Software: Mathcad calculators prepared by RE

C. Manual for Determining the Remaining Strength of Corroded Pipelines ASME B31G
– Supplement to ASME B31 Pressure Piping
– Assessment for corroded thickness between 10 to 80% of original thickness


Finite Element Analysis (FEA) of entire piping system
– Piping resistance and flexibility analysis in accordance with ASME B31.3
– Software: Algor PipePak (nowadays Autodesk Simulation
– Structural analysis of pressure vessels
– Structural software: Autodesk Robot Structural Analysis


– Fitness for Service (FFS) approach for Maintenance/Shut down
– Remaining strength assessment
– Acceptance criteria determining minimum safe wall thickness or Maximum Allowable Operating Pressure (MAOP) (also known as Maximum Allowable Working Pressure – MAWP)
– Components (straight pipe and pipe bends, vessel cylinder, dome ends, nozzles and supports) or entire system evaluation (pressure piping and vessels)
– Thorough assessment of piping and vessels – Finite Element Analysis (FEA) including offshore specific load conditions

Key word: Rig Engineering, Pressure Piping & Vessels, ASME B31.3, ASME BPVC Sec. VIII Div. 1, ASME B31G, DNV RP-F101, API 579-1/ASME FFS-1, Corroded Pipelines &Vessels Evaluation, Fitness For Service, Algor PipePak (Autodesk Simulation), Codware Compress, Autodesk Robot Structural Analysis