Rais­ing the stan­dard on bolted joints

DEMM Engineering & Manufacturing - - CONTENTS -

Joint in­tegrity is the cor­ner­stone of safe and leak-free oper­a­tion in a pres­sur­ized sys­tem. Cor­rect as­sem­bly is one of the pri­mary fac­tors in­te­gral to the in­tegrity of a bolted joint. Up un­til now bolt­ing tech­ni­cians have not been held to the same com­pe­tence stan­dards as welders.

How­ever, their work ob­jec­tives are di­rectly com­pa­ra­ble. For ex­am­ple, when com­par­ing bolted and welded joints in the oil and gas in­dus­try, stan­dards are very dif­fer­ent. Sim­i­lar dis­par­i­ties ex­ist in other ma­jor in­dus­tries, in­clud­ing min­ing and en­ergy, in­fra­struc­ture and process en­gi­neer­ing, where pres­sur­ized joints are in­volved.

When deal­ing with welded joints, en­gi­neers need to en­sure they have strong ma­te­rial con­trol, doc­u­mented and ap­proved pro­ce­dures and for­mally coded welders to per­form the task. In ad­di­tion welds are tested us­ing non-de­struc­tive tech­niques and ver­i­fied through hy­dro and/or gas-test­ing meth­ods. All of this is sup­ported through fully doc­u­mented trace­abil­ity. These manda­tory stan­dards for welded joints have not typ­i­cally been ap­plied to bolted con­nec­tions.

How­ever, things are chang­ing and 2013 proved to be a land­mark year for those con­cerned with the man­age­ment and as­sem­bly of bolted joints as two ma­jor stan­dards were pub­lished high­light­ing the re­quire­ments for com­pe­tent bolt­ing.

The Amer­i­can So­ci­ety of Me­chan­i­cal En­gi­neers (ASME) up­dated the 2010 PCC-1 ‘Guide­lines for Pres­sure Boundary Bolted Flange Joint As­sem­bly’ – this now in­cludes an ap­pen­dix defin­ing the re­quire­ments for train­ing and qual­i­fi­ca­tion of en­gi­neers work­ing in the field of bolted joints.

In ad­di­tion to this, the Euro­pean Com­mit­tee for Stan­dard­i­s­a­tion (CEN) re-pub­lished EN1591 Part 4 with mod­i­fi­ca­tions. This is now re­ferred to as ‘Flanges and their Joints – Part 4: Qual­i­fi­ca­tion of per­son­nel com­pe­tency in as­sem­bly of the bolted con­nec­tions of crit­i­cal ser­vice pres­surised sys­tems’.

Hy­dratight pi­o­neered the con­cept of treat­ing the bolted joint as though it were a weld and has prac­tised the es­sen­tials of this stan­dard for more than 20 years. The com­pany has pro­vided for­mally qual­i­fied and com­pe­tent bolt­ing craft per­son­nel dur­ing this time, with all craft per­son­nel un­der­tak­ing class­room train­ing, fol­lowed by prac­ti­cal work­shops and ex­am­i­na­tion be­fore be­ing per­mit­ted to work in the field on live projects.

Through the pub­li­ca­tions of these stan­dards, in­dus­try has been pro­vided guid­ance in the as­sem­bly and as­sur­ance of bolted con­nec­tion sim­i­lar to the con­trol and as­sur­ance of the welded joint.

Like the welded joint, field per­son­nel will have to prove their com­pe­tency ev­ery three years, doc­u­ment their ac­tiv­i­ties us­ing pre-ap­proved pro­ce­dures and trace­able bolt loads and main­tain a per­ma­nent record for fu­ture ref­er­ence.

Pro­vid­ing these stan­dards are rig­or­ously fol­lowed, as­set own­ers can ex­pect sig­nif­i­cant pay­back; re­duced leaks, im­proved safety per­for­mance, projects built or re­turned to ser­vice on sched­ule and within budget.

Joint in­tegrity data man­age­ment

Hy­dratight wel­come the pub­li­ca­tion of these up­dates to in­dus­try stan­dards. We have cham­pi­oned the con­cept of treat­ing bolted joints to be con­sid­ered as crit­i­cal as welded con­nec­tions.

As a re­sult, we have de­vel­oped train­ing and com­pe­tency pro­grammes to en­sure that all bolt­ing op­er­a­tions are car­ried out with an un­com­pro­mis­ing ap­proach to safety.

While these com­pre­hen­sive train­ing pro­grammes are manda­tory for Hy­dratight’s craft per­son­nel, they are also avail­able to cus­tomers and to the gen­eral mar­ket.

Clearly de­fined pro­ce­dures and ac­cep­tance qual­ity stan­dards sup­ported by well-main­tained data are cru­cial for as­sur­ing leak free joints.

As stan­dards for joint clo­sure and main­te­nance track­ing have not pre­vi­ously ex­isted, as­set own­ers/oper­a­tors have adopted dif­fer­ent sys­tems. Some rely on the mem­ory of the main­te­nance team; oth­ers keep paper-based data records and oth­ers use spread­sheet-based track­ing reg­is­ters. Typ­i­cally all of these are prone to fail­ure over time.

As as­sets age and their na­ture of use changes (e.g. con­tain dif­fer­ent and/or more cor­ro­sive con­tents) risks in­crease. With the pass­ing of time, per­son­nel and rigid­ity of data stor­age and re­trieval sys­tems find­ing the cor­rect in­for­ma­tion be­comes more dif­fi­cult. This po­ten­tially ex­poses ma­jor prob­lems.

Well thought out and proven soft­ware­based in­tegrity man­age­ment sys­tems can pro­vide a so­lu­tion to mit­i­gat­ing risk on bolted f langes, by pro­vid­ing trace­abil­ity through­out joint life.

In Hy­dratight’s ex­pe­ri­ence (we typ­i­cally work on as­sets with 50,000-plus bolted joints) the in­stal­la­tion of a proven soft­ware so­lu­tion is only one el­e­ment. Fur­ther­more, by work­ing in part­ner­ship with oper­a­tors, it is pos­si­ble to sig­nif­i­cantly re­duce leaks. How­ever, true joint in­tegrity man­age­ment is not just some­thing you can buy; it is some­thing you must ‘buy’ into.

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