Nomenclaturea Pipe inside radiusb Pipe outside radiusD Pipe outside diameterDi Pipe inside diameterdr Change in pipe radiusPi Internal design pressurePo External pressurer Pipe radius at any point along the pipe wall thicknesst Pipe nominal wall thicknesssh Hoop stress = circumferential stress = tangential stress, exact value from thick wall

pipe formulashmHoop stress from the modified thin wall pipe formulasho Hoop stress from the original thin wall pipe formulasho' Hoop stress from the original thin wall pipe formula without considering external

pressuresr Radial stress