Lloyds Pressure Vessels – Fusion Welded Pressure Vessels – Lloyds Class I Pressure Vessel Manufacturer

We have Class 1 approval from Lloyd’s Register Group for the manufacture of fusion welded pressure vessels in accordance with Lloyd’s Register Rules and Regulations for the Classification of Ships, Part 5, Chapter 17. Lloyds rules pressure vessel fabricator

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Requirements for Fusion Welding of Lloyds Rules Pressure Vessels (LR pressure Vessels) and Piping Section
1 General
2 Manufacture and workmanship of fusion welded pressure vessels
3 Repairs to welds on fusion welded pressure vessels
4 Post-weld heat treatment of pressure vessels
5 Welded pressure pipes
6 Non-Destructive Examination
■ Section 1
General
1.1 Scope
1.1.1 The requirements of this Chapter apply to the welding of pressure vessels and process equipment, heating and steam raising boilers and pressure pipes. The allocation of Class is determined from the design criteria referenced in Chapters 10, 11 and 12.
1.1.2 Fusion welded pressure vessels will be accepted only if manufactured by firms equipped and competent to undertake the quality of welding required for the Class of vessel proposed. The manufacturer’s works are to be approved in accordance with the requirements specified in Materials and Qualification Procedures for Ships, Book A Procedure MQPS 0-4.
1.1.3 For pressure vessels which only have circumferential
seams, see Ch 10,1.5.4 and Ch 11,1.5.5.
1.2 General requirements for welding plant and welding quality
1.2.1 In the first instance, and before work is commenced, the Surveyors are to be satisfied that the required quality of welding is attainable with the proposed welding plant, equipment and procedures in accordance with
the guidelines specified in Materials and Qualification Procedures for Ships Book A, Procedure 0-4.
1.2.2 All welding is to be in accordance with the requirements specified in Chapter 13 of the Rules for the Manufacture, Testing and Certification of Materials (hereinafter referred to as the Rules for Materials).
1.3 Manufacture and workmanship of fusion welded pressure vessels
1.3.1 Pressure vessels are to be constructed and examined in accordance with the requirements specified in Chapter 13 of the Rules for Materials, unless more stringent requirements are specified.
■ Section 2
Manufacture and workmanship of fusion welded pressure vessels
2.1 General requirements
2.1.1 Prior to commencing construction, the design of the vessel is to be approved where required by Ch 10,1.6 and Ch 11,1.6.
2.1.2 Pressure vessels will be accepted only if manufactured by firms that have been assessed and approved in accordance with MQPS 0-4.
2.2 Materials of construction
2.2.1 Where the construction requires post weld heat treatment, consideration should be given to certifying the material after subjecting the test pieces to a simulated heat treatment.
2.3 Tolerances for cylindrical shells
2.3.1 Measurements are to be made to the surface of the parent plate and not to a weld, fitting or other raised part.
2.3.2 In assessing the out-of-roundness of pressure vessels, the difference between the maximum and minimum internal diameters measured at one cross-section is not to exceed the amount given in Table 17.2.1.
2.3.3 The profile measured on the inside or outside of the shell, by means of a gauge of the designed form of the shell, and having a chord length equal to one-quarter of the internal diameter of the vessel, is not to depart from the designed form by more than the amount given in Table 17.2.1. This amount corresponds to x in Fig. 17.2.1. RULES AND REGULATIONS FOR THE CLASSIFICATION OF SHIPS, July 2009
Part 5, Chapter 17
Sections 1 & 2
LLOYD’S REGISTER 1
Table 17.2.1 Tolerances for cylindrical shells for LLoyds Rules Pressure Vessel manufacturers
Nominal internal diameter of vessel in mm
Requirements for Fusion Welding of Pressure Vessels and Piping
2.3.4 Shell sections are to be measured for out-of roundness, either when laid flat on their sides or when set up on end. When the shell sections are checked while lying on their sides, each measurement for diameter is to be repeated after turning the shell through 90° about its longitudinal axis.
The two measurements for each diameter are to be averaged, and the amount of out-of-roundness calculated from the average values so determined.
2.3.5 Where there is any local departure from circularity due to the presence of flats or peaks at welded seams, the departure from designed form shall not exceed that of Table 17.2.1.
2.3.6 The external circumference of the completed shell is not to depart from the calculated circumference (based upon nominal inside diameter and the actual plate thickness) by more than the amounts given in Table 17.2.2.
■ Section 3
Repairs to welds on fusion welded pressure vessels
3.1 General
3.1.1 Repairs to welds on fusion welded pressure vessels are to be in accordance with the requirements of Chapter 13 of the Rules for Materials.
■ Section 4
Post-weld heat treatment of pressure vessel fabricators
4.1 General
4.1.1 Post-weld heat treatment of fusion welded pressure vessels are to be in accordance with the requirements of Chapter 13 of the Rules for Materials.
■ Section 5
Welded pressure pipes
5.1 General
5.1.1 Fabrication of pipework is to be carried out in accordance with the requirements of Ch 13,5 of the Rules for Materials.
5.2 Welding workmanship
5.2.1 Preheating is to be effected by a method which ensures uniformity of temperature at the joint. The method of heating and the means adopted for temperature control are to be to the satisfaction of the Surveyors.
5.2.2 All welding is to be performed in accordance with the approved welding procedures in this Section by welders who are qualified for the materials, joint types and welding processes employed.
5.2.3 Welding without filler metal is generally not permitted for welding of duplex stainless steel materials.
5.2.4 All welds in high pressure and high temperature pipelines are to have a smooth surface finish and even contour; if necessary, they are to be made smooth by grinding.
5.2.5 Check tests of the quality of the welding are to be carried out periodically at the discretion of the Surveyors.
RULES AND REGULATIONS FOR THE CLASSIFICATION OF SHIPS, July 2009
Part 5, Chapter 17 Sections 2 to 5 2 LLOYD’S REGISTER
■ Section 6
Non-Destructive Examination
6.1 General
6.1.1 Non-Destructive Examination (NDE) of pressure
vessels and piping is to be performed in accordance with the
requirements of Ch 13,4 and 5 of the Rules for Materials.
Other Pressure Vessel design code info. can be found with the links below
PD5500, EN286, DNV, ASME, LLOYDS, 97/23/EC, EN13445, 87/404/EEC, 2009/105/EC, ABS, BS5169

Please email your requirements or complete our pressure vessel enquiry forms – for Lloyds Register Pressure Vessels or Air Receivers