To calculate the cross section area of a steel pipe:


A = 0.785d_{i}^{2 }
where
A = crosssectional area of pipe (Square Inches)
d_{i} = inside diameter (inches)

To calculate the weight of empty steel pipes:


w_{p} = 10.6802 t (d_{o}  t)
where
w_{p} =weight of steel pipe (Pounds per Foot Pipe)
t = pipe wall thickness (Inches)
d_{o} = outside diameter (inches)

To calculate the weight of water in pipes filled with water:


w_{w} = 0.3405 d_{i} ^{2}
where
w_{w} = weight of steel pipe filled with water (Pounds per Foot Pipe)
d_{i} = inside diameter (inches)

To calculate the outside surface area of steel pipes:


A_{o} = 0.2618 d_{o}
where
A_{o} = outside area of pipe  per foot (Square Feet)
d_{o} = outside diameter (inches)

To calculate the inside surface area of steel pipes:


A_{i} = 0.2618 d_{i}
where
A_{i} = inside area of pipe  per foot (Square Feet)
d_{i} = inside diameter (inches)

To calculate the area of the metal:


A_{m} = 0.785 (d_{o} ^{2}  d_{i} ^{2})
where
A_{m} = area of the metal (Square inches)
d_{i} = inside diameter (inches)
d_{o} = outside diameter (inches) 