CLIENT BACKGROUND

Coke drums tend to operate on 24-hour cycles where they experience extreme changes in temperature. This temperature cycling creates rapid changes in material expansion and integrity, with most delayed coking sites having leakage problems. This occurs in the joint between the Bottom De-heading Valve (BUD) and the coke drum or coke drum transition spool.

CHALLENGES

If escalated, joint leakage can result in ignition requiring the unit to be taken offline to repair the joint. This leads to several days of lost production from the unit. In addition, there is cost associated with the periodic tightening of the joints and the potential for over-tightening of the bolts, leading to damage of the valve body at the studded hole

RT-Bolt - Coke Drum Bottom Deheading

120 RT-Bolts, with hardened washers and machined nuts, all specially coated, ready for installation on site.

RT bolt

SOLUTION

We’ve deployed the RT-Bolt system across several delayed coker units to ensure accurate joint assembly, monitor bolt load during operation and continue to monitor the bolt load after retightening. To overcome common problems with bolts galling, the Rt-Bolts for this application are supplied with a special coating, hardened coated and machined washers, and machined and coated nuts.

CONCLUSION

Rt-Bolt has enabled the joints to maintain a significantly higher (>30%) residual bolt load, reducing both the frequency of leakage and re-tightening on the bolts. This usage has shown that a significant factor causing the previous leakages has been due to insufficient bolt load achieved during the initial assembly.