Determine buoyancy of bare and concrete coated steel pipe in water and mud

Bouyancy of bare & concrete coated

To find the buoyancy in water in lb/ft :



for bare pipe:

for coated pipe:

To find the buoyancy in mud in lb/ft :

for bare pipe:

for coated pipe:

Example 1. Find the buoyancy of steel pipe with 20-inch OD and 1/2-inch wall thickness in water. What thickness ofconcrete coating would be required to give this pipe a negative buoyancy of 100 lb/ft (Wc =143)?

Answer: t1 = 3.8 in of concrete coating.

Example 2. Bottom conditions at a certain crossing that require the pipe to have a negative buoyancy of at least 50 lb/ft. Let’s check to see if a 10-inch pipe having a 2-inch coating of concrete (Wc = 143) has sufficient negative buoyancy.

Answer: t1 = -53.3 lb/ft; so coated pipe meets design requirements.