IBR boiler riveting: shearing resistance per pitch length in double shear Let d = rivet diameter, τ = allowable shear stress, and n = number of rivets per pitch length. According to I.B.R., determine the shearing resistance required to shear off the rivets (double shear). Choose the correct expression.

Given
• Boiler joint design per I.B.R. (Indian Boiler Regulations).
• Double-shear condition; n rivets per pitch length.

Concept/Approach
Per I.B.R. empirical provisions, the shearing resistance in single shear is taken as 0.9375 · d^2 · τ · n (using an effective shear area factor). For double shear, multiply by 2:

Shearing resistance (double shear) = 2 × 0.9375 · d^2 · τ · n = 1.875 · d^2 · τ · n

Common pitfall
Do not confuse with the theoretical area πd^2/4; I.B.R. uses codified effective factors for boiler riveting.

Final Answer
1.875 · d^2 · τ · n