Let d represent the nominal diameter of a bolt measured in mm; the initial tightening tension in kg for establishing a leak-proof fluid seal, such as on a steam engine cover, is determined via the formula_______________?
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Answer: E. 168 d
Explanation
Empirical design formulas for pressure vessel covers set initial bolt tension proportional to nominal diameter. Multiplying the nominal diameter in millimeters by 168 yields the required tightening tension in kilograms. This specific multiplier ensures adequate gasket compression without overstretching the fastener steel. Steam engines and pressure vessels require precise bolt preload to contain high pressure steam safely. Initial tightening tension prevents joint separation during operational thermal expansion cycles. Nominal diameter represents the major outer thread diameter of the threaded bolt fastener.
Proper bolt tensioning prevents dangerous steam leaks and catastrophic gasket blowouts in boilers. Maintenance technicians use calibrated torque wrenches to achieve specified initial bolt tensions. Empirical rules derived from historical steam engineering practices guide safe bolt sizing calculations. Coefficients like 102 or 124 underestimate the required clamping force for steam seals. Alternative multipliers such as 151 fail to match the standard empirical steam cover formula. Using arbitrary tension values risks either joint leakage or permanent fastener plastic deformation.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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