Technology Share 5
Criterion of Online leak sealing Clamps Design
1. Summary
In clamp sealing method, it involves two fixture structure: flange leak repair clamp and tube leak repair clamp.Tube clamp includes straight pipe clamp, reduced pipe clamp, elbow clamp, and tee clamp etc. The physical and chemical parameter of the leaking medium survey and geometric parameter of leaking location survey involved in the clamp design should be carried out according to ASME Sec. VIII pressure vessel codes and fabricated to the highest standard.<Generic Specification for Online Leak Sealing Clamps of Pressure Equipment>
2. Online Leak sealing Clamp function
2.1 The fixture structure should cover the outer surface of the leak leaking location and form the filling cavity for containing the injection sealant, which is the sealing guarantee system for newly established sealing structure of sealant packing without overflowing, and of maintaining injection pressure ascending to reach the sealing pressure required for stopping leakage.
2.2 The fixture rigidity should meet the pressure sum of leaking system and sealant extrusion，which is the rigidity guarantee system for newly established sealing structure free from deformation in application.
2.3 There should set injection port as the filling cavity passage for the injection sealant in the clamp for adaptor and injection gun connection.
3. Online leak sealing Clamp design criterion
3.1 The online leak repair clamp carrying injection pressure and leaking medium pressure should apply the mental material and meet the thickness and rigidity conditions and does not allow the plastic deformation in application.
3.2 The structure at Online leak sealing clamp joint should meet the strength condition and does not allow the breaking in application.
3.3 It should not generate the pulling stress on the leaking defect in selection of leak sealing clamp structure.
3.4 The match tolerance at the touching location between online leak sealing clamp and leaking surface should be proper to meet the sealing stress requirement.
3.5 The filling cavity forming between clamp and outer surface of leaking location for containing injection sealant should follow the following specifications:
（1） The width of the filling cavity for tube clamp should cover the leaking defect, 15mm at least to the clamp end plate one side. The height of the filling cavity (injection sealant thickness) should be proportional to the sealing system temperature, selecting among 5mm～20mm.
（2） The fixture is advisable to be designed as raised tongue type, with the largest tongue width slightly less than minimum flange connection gap.
（3） The leakage at the weld joint of the flange and tube and threaded connection or welding neck flange leakage should be designed as box type of flange clamp in Annex A.
（4) The clamp width should be determined to extend for 10～20mm from median side to both sides. In sealing enhancement structure, it should increase clamp width based on the groove width.
3.6 The sealing clamp injection ports quantity should be up to following specification:
（1） The injection ports setting quantity of flange clamp should be equal to flange connection bolts.
（2） The center pitch of pipe clamp injection ports should be less than or equal to 100mm.
3.7 The fixture should take rational subdivision design for easy installation.
3.8 Online leak sealing Clamp design personnel should obtain the special equipment operator certificate issued by General Administration of Quality Supervision, Inspection and Quarantine before they works in the field of clamp design for online leak sealing operation
3.9 Based on the leaking structure characteristics, the fixture could be designed as altered clamp structure as recommended in Annex A or Sealing enhancement structure in Annex B.
3.10 The performance level of sealing clamp fastening bolts should select stud bolt graded not less than grade 8.8
