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Lloyds Pressure Vessels - Fusion Welded Pressure Vessels - Class 1
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.
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Requirements for Fusion Welding of 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
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 vessels
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,
EN13345,
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