Seamless steel tube under external pressure and internal force, fear of burst pipes as you say, is not referring to the force? Seamless pipe used most of force in the design of the boiler, pipes can withstand the pressure and pipe diameter, wall thickness, temperature, use the relationship to the environment.
Can tell you a formula that is inside the boiler design of pipe wall thickness calculation formula can be under pressure on the back of wall thickness: PD/(2Ya+p).
Where p is the pressure, d is the diameter, and y is the attenuation coefficient, take 1, a is the stress this to choose a corresponding material shall be according to the temperature stress.
Specific reference to boiler strength calculation standards: 16507, 16508. tubes of small diameter, wall thickness 3 mm, for 3, 4 MPa above is no problem.
Tensile strength σ of the set material, pressure p, outer diameter d; pipes wall thickness δ = (P*D)/(2*/σ s) where s is the safety factor; p less than 7MPa,S select S=8; p less than 17.5MPa,S select S=6; p greater than 17.5MPa,S select S=4; we made safety S=6; -20 tensile strength of 410MPa steel, it tube can withstand a pressure of p = (2* σ/S* δ)/D = (2*410/6*3)/(10+6) =26.25MPa> set 17.5 safety factor of S=4 can withstand the pressure of the pipe P= (2* σ/S* δ)/D = (2*410/4*3)/(10+6) =39.375MPa