{"id":99687,"date":"2026-04-08T08:02:36","date_gmt":"2026-04-08T08:02:36","guid":{"rendered":"https:\/\/irwindevc.wpenginepowered.com\/?p=99687"},"modified":"2026-05-29T04:10:44","modified_gmt":"2026-05-29T04:10:44","slug":"pe-lined-pipe-fabrication-best-practices","status":"publish","type":"post","link":"https:\/\/irlservice.com\/en\/pe-lined-pipe-fabrication-best-practices\/","title":{"rendered":"5 Best Practices for PE Lined Pipe Fabrication & Engine Room Scanning"},"content":{"rendered":"
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Best Practices for Isometric Drawings, Scan Data & PE Lined Pipe Fabrication<\/h1>\n

From the owner of the largest pipe and pressure vessel rotational lining factory in China<\/p>\n\n \n

As the owner of the largest pipe and pressure vessel rotational lining factory in China, I have been recently looking at many drawing packages related to BWTS and EGCS retrofits. Specifically, I look at many sets of isometric pipe drawings for fabrication and PE lining of the spools. The drawings are all over the place in terms of quality and information \u2013 so I hope to share some of the best practices.<\/p>\n\n

Since scanning technology and the associated software packages have really only come into their own in the last few years, many otherwise technically qualified individuals are not sure what they can expect from a quality set of drawings taken from scan data.<\/p>\n\n \n

Scan Data & Point Clouds: What Really Matters<\/h2>\n

When an engine room or other structure is scanned, the first step is to create a point cloud<\/strong> \u2013 a bunch of 3D coordinates collected by the scanner. Software then crunches this data, smooths it out and filters it to create a dimensioned space that other dimensioned objects can be placed (like that new pipe run for your BWTS).<\/p>\n\n

While there are differences in accuracy between different systems and scanning modes, the theoretical accuracy of a scanner has very little to do with the ultimate accuracy of the drawings<\/strong>. For example, if you have a scanner that can scan to 0.5mm accuracy, you cannot be confident in the position of a pipe tie\u2011in if there is 3mm of rust and paint on the pipe you are scanning. You definitely cannot hope to have that accuracy if the deck plates were never lifted and the pipe run in the drawing is just an extrapolation of the parts that poke above the deck plates.<\/p>\n\n

I am a big believer that the person who does the actual scan should be the same person that creates the isometric drawings.<\/strong> There will be many judgement calls, and only a knowledgeable and experienced technician who did the scanning will know how to make them. For example:<\/p>\n

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  • Was the vessel built in a dockyard with CNC fit\u2011up of the spools, so you can count on all pipes being parallel and fabricated according to best practices?<\/li>\n
  • Or was it built in a dockyard without those resources \u2013 all pipes are \u201cspaghetti runs\u201d where machinery was placed and pipes just welded to fit?<\/li>\n <\/ul>\n

    In the first case, I am much more confident we can create tie\u2011in spools directly from the isometrics. In the second case, I will specify more calibration spools.<\/p>\n\n \n

    My First Pet Peeve: \u201cFit Up In Situ\u201d<\/h2>\n

    If you have quality scan data, I never ever want to see a large spool specified \u201cfit up in situ\u201d or \u201cleave fittings loose\u201d or \u201cfor site fabrication.\u201d<\/strong> This indicates low professionalism by the designer, or a lack of confidence in the scan data, or excessive risk aversion.<\/p>\n

    I do not care if the pipes are GRE\/GRP and everyone knows the fittings will have to be bonded in situ \u2013 I do not want to see a single large pipe specified for site fabrication in the isometrics. A professional designer with quality scan data should only specify small calibration spools<\/strong> to ensure proper tie\u2011in tolerances. If the scan data and the designer are good, even those calibration spools will likely fit.<\/p>\n\n

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    Real example:<\/strong> We have previously fabricated and coated DN1000 main condenser lines with an S\u2011elbow, branches and all fixed flanges \u2013 over 6 meters long \u2013 using a drawing taken from a scan, and it fit spot on. If your engineering company says this is impossible, it is time to interview a new engineering company.<\/strong><\/p>\n <\/div>\n\n

    Remember that every designer wants to minimize risk, but this should not be at the expense of the customer. Specifying more spools for site fabrication may increase the chance certain spools fit and reduce the designer\u2019s risk, but at the owner\u2019s expense of requiring more time and cost at the dockyard.<\/p>\n\n \n

    Never Use Scan Data from a Sister Vessel<\/h2>\n

    Sister vessels may be sisters, but they are not identical twins!<\/strong> The minimal amount of money that could be saved by using data from a sister vessel will be crushed by the additional time and cost incurred by not having optimal drawings. An engineering company that tells you about all the money you will save this way is probably more interested in making a sale than being the right partner for a successful docking.<\/p>\n\n \n

    Design for Practical Fabrication & Coating<\/h2>\n

    Rotational lining is a robust process that can apply a seamless lining to difficult geometry pipes, but do not use our ability as a crutch to make stupid designs.<\/strong><\/p>\n

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    • If a pipe goes in the engine room, it should not be more than 3 meters long<\/strong>.<\/li>\n
    • If a pipe has an elbow or branches, it should not be more than 3 meters long<\/strong>.<\/li>\n
    • No more than two elbows or one elbow and one branch<\/strong> on any single pipe (manifolds are the exception).<\/li>\n
    • If you cannot grind an interior weld, then do not make the pipe that way<\/strong>.<\/li>\n
    • Flanges save money \u2013 they do not cost money.<\/strong><\/li>\n <\/ul>\n\n \n

      The Fabricator Needs to Talk Directly to the Designer<\/h2>\n

      Even the best designers will, on occasion, create a design that is not optimal for fabrication, coating or fitting. The fabricator is the expert on fabrication \u2013 so let the fabricator collaborate with the designer<\/strong>. This does not mean talking to a project manager who acts as a go\u2011between.<\/p>\n

      When I get a set of drawings that includes a note like \u201cIf you have any questions or would like to suggest any changes, you can reach the designer at...\u201d<\/em> \u2013 that tells me I am working with an experienced company that does not want to waste time or money.<\/p>\n

      Many excellent designers, following a 15\u2011minute drawing review with the fabricator, will make simple changes that result in thousands of dollars in savings. Example: replacing 1D elbow fittings with a 3D bent elbow for smaller diameter pipes \u2013 a bent pipe is cheaper, faster to fabricate, and easier to coat.<\/p>\n

      Being a stickler for quality drawings is the best way a fabricator can prevent disputes.<\/strong><\/p>\n\n \n

      Always Include a 3D Rendering<\/h2>\n

      Use a software package that will create a 3D rendering for each isometric. I have one expert on my staff who is really good at reading isometrics \u2013 and when I cannot figure out which way something should be fabricated, I have to ask him (and this is after looking at thousands of drawings). Include a 3D rendering, and then everyone becomes an expert at reading the drawings.<\/strong><\/p>\n\n \n

      Never Spec an Existing System Pipe to Be Modified In Situ<\/h2>\n

      Never specify an existing system pipe to be modified in situ to accommodate a retrofit unless you have a plan on how to coat that pipe.<\/strong> Spray\u2011applied \u201cgalvanizing\u201d and most two\u2011part epoxies that can be used for in situ coating are junk. Even if you have a good product:<\/p>\n

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      • Can the surface be properly prepared?<\/li>\n
      • Is the repair coating compatible with the pre\u2011existing coating?<\/li>\n <\/ul>\n

        If you are still wondering about the right answer, let me help you: the answer will be \u201cNO\u201d.<\/strong> If you are planning on minimizing docking time, you need a new factory\u2011coated pipe<\/strong> that will be connected via a flange connection to the existing pipeline.<\/p>\n\n \n

        If a Pipe Does Not Fit \u2013 Never Delay<\/h2>\n

        Remember: if you have good drawings, the only pipes that will not fit are the calibration spools.<\/strong> Immediately ask the dockyard to make two identical spools that do fit:<\/p>\n

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        1. Let the vessel sail with an uncoated fitted spool<\/strong>.<\/li>\n
        2. Send the second spool for coating, then after coating send it to the vessel to be fitted.<\/li>\n <\/ol>\n

          We make the calibration spools small \u2013 so they are easy to fit, cheap to ship, fabricate and coat.<\/p>\n\n \n

          Coating Allowances Are Important<\/h2>\n

          We typically machine the PE on the flanges to 2mm. Sometimes vulcanized rubber coatings can be up to 6mm thick. I always want to see a coating allowance specified on the fabrication drawings<\/strong> \u2013 because this tells me it has been considered in the design.<\/p>\n

          If a designer calls me up and asks how to properly specify the coating allowance, then I know I am dealing with a good designer<\/strong>.<\/p>\n\n<\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"

          As the owner of the largest pipe and pressure vessel rotational lining factory in China, I have been recently looking at many drawing packages related to BWTS and EGCS retrofits. <\/p>","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"footnotes":""},"categories":[30,27,25,29],"tags":[],"class_list":["post-99687","post","type-post","status-publish","format-standard","hentry","category-coating","category-lining","category-marine","category-ship-repair"],"_links":{"self":[{"href":"https:\/\/irlservice.com\/en\/wp-json\/wp\/v2\/posts\/99687","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/irlservice.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/irlservice.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/irlservice.com\/en\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/irlservice.com\/en\/wp-json\/wp\/v2\/comments?post=99687"}],"version-history":[{"count":0,"href":"https:\/\/irlservice.com\/en\/wp-json\/wp\/v2\/posts\/99687\/revisions"}],"wp:attachment":[{"href":"https:\/\/irlservice.com\/en\/wp-json\/wp\/v2\/media?parent=99687"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/irlservice.com\/en\/wp-json\/wp\/v2\/categories?post=99687"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/irlservice.com\/en\/wp-json\/wp\/v2\/tags?post=99687"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}