What to send the fabricator with the KMD: package contents and checklist

Why drawings alone are not enough

A sheet with a shipping element gives dimensions, assembly and welding. The steel grade for every item, the coating system and colour, the scope of weld inspection, the documents for the metal, the marking and packing requirements and the delivery address it does not give, although without them metal is not ordered and the piece is not released to the shop. So a package is sent with the KMD, in which every question is settled once and the same way on all sheets.

The composition of the main KMD set and of the additional drawings is described in the article KM and KMD stages: composition of the sets, the rules for drawing up the sheets in the article Drawing rules for KM and KMD. They are not repeated here: we collect what must be sent to the fabricator and what the fabricator checks first.

The standard for the execution of steel structures, DSTU EN 1090-2:2019, calls such a set the execution specification. Before the works start, the information and requirements must be agreed, including the execution class, the preparation grades of the surface for coating, the tolerance classes and the additional information from the list in Annex A of the standard. The package you send is exactly such a set for your project.

What the package consists of

The table lists the documents of the package. Some of them are part of the KMD set itself, others the fabricator prepares or asks you for.

The composition of the KMD depends on the type of structure. The full list of summary schedules and additional drawings is given in the article on the composition of the sets.

Metal: steel grade and documents

The steel grade must appear in every item: in the specification and in the technical requirements. If the grade is missing, the fabricator does not guess it from the section: the purchase of metal, the welding consumables and the galvanizing depend on it. The main grades we fabricate from are St3, S245, S345 and 09G2S; how to choose a grade is covered in the article Steel grade selection.

If a structure has several grades, they are assigned to items and not mixed within one joint. For galvanizing it is better to keep one grade within a structure: the coating then looks more even. Items are submitted for galvanizing in bundles by steel grade, with tags stating the grade. If the structure is to be galvanized, tell the steel supplier: he will pick rolled steel with a suitable chemical composition.

The grade and quality of the metal are confirmed by the manufacturer’s data sheets or certificates or by laboratory test reports. Write in the request which documents are needed with the products, and we agree the list before fabrication starts.

Welding and inspection: what to put in the technical requirements

The type and size of a weld are marked by the drawing rules, see Drawing rules for KM and KMD; how to read the letters and numbers of joint types is covered in the article on weld joint types. Leg sizes, lengths, the welding sequence and the places where full penetration is needed must agree on all sheets, because the fabricator works from the drawing, not from an assumption.

The scope of inspection is stated in the request and the technical requirements. All welds are visually inspected; the welds the project names are checked by ultrasound. We do not carry out radiographic inspection, so if the project requires it, say so at the request stage. The list of welds and the method for each is conveniently given in a schedule of shop welds. What exactly is checked in production is described in the article Quality control of steel structures.

After Amendment No. 1 to DBN V.2.6-198:2014 the project must state the execution class of the structures, EXC1–EXC4 (cl. 5.1.5, Annex U); the strictness of the requirements for execution and inspection depends on it. If the execution class is stated, it goes in the general data. A weld that cannot be reached, and a joint where the welds cannot be made, are changed before fabrication begins, not in the shop.

Coating: zinc, paint, colour

The coating is named for each element or group separately: hot-dip galvanizing, powder coating, painting to a system, zinc followed by paint. Write what exactly is needed, not «corrosion protection»: surface preparation, the process route and the lead time depend on it. The coating thickness is stated as the project requires; for the thickness of hot-dip zinc and how it is measured see the article Zinc coating thickness.

Powder coating and painting need a colour from the RAL catalogue. If an item will be painted or powder-coated after galvanizing, say so in advance: the requirements for surface preparation are agreed separately. For welds, edges and areas with surface defects to be painted, the standard has three preparation grades, P1–P3 (EN ISO 8501-3), which are stated in the execution specification where needed.

For hot-dip galvanizing the structure must be ready: holes for liquids, zinc and air to enter and leave hollow elements, drain holes, hanging points, dressed edges, welds free of slag. Holes and cut-outs are easier to make before assembly, so they are shown in the KMD and not added in the shop. All this is covered in the articles Design for hot-dip galvanizing and the preparation checklist. Zones where the coating must be different or absent, for example the contact surfaces of slip-resistant connections, are marked on the drawing; see the article Bolted connections.

Dimensions, mass and transport

DBN V.2.6-198 recommends dividing a structure into shipping elements with regard to the type of transport, the dimensions of vehicles and the lifting and handling equipment of the erectors (cl. 5.2.1). Galvanizing adds to this: a mark must fit in the bath and survive being hung. The dimensions and mass of each mark are checked before the KMD is issued, not after fabrication.

If a piece does not fit the bath, it is sometimes dipped in two goes, turned over. This happens less often and the method is agreed separately; it is simpler to split the structure into marks already in the KMD.

Transport elements and the loading scheme

Where needed, transport elements that keep the geometry of a mark during carriage are added to a shipping element, and erection elements such as lugs or loops: they count in the mass of the shipping mark if they are shown on its drawing. A loading scheme for transport is prepared, where needed, at the fabricating works; if you need it, say so in the request.

Tolerances, marking, packing and shipping

The fabricator usually cannot take these requirements from the detail sheets. They are written in the technical requirements or in a separate paragraph of the request.

Tolerances

Final dimensions on the drawing are given after all technological operations. Allowances and shrinkage are not shown on drawings; the fabricator’s technological documentation sets them. If the piece has requirements stricter than usual, for example on the position of holes in a flange for an anchor cage or the next section, put them in the technical requirements: such holes are checked in the shop. For this DSTU EN 1090-2 provides essential and functional tolerances, and a tolerance class can be stated for individual elements of the structure.

Marking

Every shipping mark is identified at all stages of production, and the mark is taken from the KMD: the same on the drawing, in the schedule and on the erection scheme. For galvanized elements the marking method is agreed with the fabricator: labels, glue and marker stains are removed from the surface before pickling. If there are zones where marks must not remain visible after completion, they are stated separately.

Packing and shipping

Galvanized items are stacked on spacers so that air moves freely; shrink-wrap is not used, because it holds water and gives «wet storage stains». Long elements are lifted not by a single point but with a spreader beam. The delivery address and the person receiving the load are stated in the request; the delivery terms are agreed in the contract.

If erection goes in stages, mark which marks are needed first. The order of production and shipping depends on it; some of the drawings can be released to production earlier without waiting for the rest of the set.

Erection connections, fasteners and erection schemes

The type of each erection connection, welded or bolted, is shown on the joints and in the schedule of erection metal items. For a bolted joint the diameter, class, assembly standard, type of holes, preparation of contact surfaces and tightening method are needed; the list is given in the article Bolted connections in steel structures. We supply the fasteners for the joints together with the structures, so the schedule must be complete — class, assembly standard, diameter, length and quantity.

Erection is done by our partner construction company, so the erection scheme should contain the sequence, the erection elements (lugs, loops, seats) and the places where the fabricator leaves an allowance for fitting. Anchor bolts and embedded parts are covered separately: Anchor bolts for poles and masts and anchor cages. If the package has base joints, state the loads on the foundation. We design the foundation by separate order and for a separate fee; most often we simply pass the loads on.

What the fabricator clarifies after receiving the package

After reading the package the fabricator comes back with questions. Each of them stops the start until it is answered, so it is better to answer them in the package.

• what steel grade is in the items where it is not stated, and whether it is one grade within the structure;
• whether the piece is galvanized and to which system, and if painted, which system and which RAL;
• what to do with elements that do not fit the bath: split into marks, dip in two goes or change the joint;
• why the quantity or mass in the schedule differs from the specification;
• which welds to inspect and by what method;
• which documents are needed with the products;
• whether a trial assembly is needed before shipping and to what extent;
• who erects and in what order the marks are needed;
• where and to whom to ship.

We carry out the trial assembly of joints before shipping, including flanged pairs of sections, in the shop; if it is needed, it is stated in the request.

Typical package defects

• no rolled steel specification or schedule of shipping elements: the amount of metal and work cannot be determined;
• contradictions between sheets: the mass or quantity in the schedule does not match the specification, the element mark on the scheme differs from that on the drawing, the KMD erection scheme does not match the KM layout scheme;
• the steel grade is stated not in all items, or it is not stated whether it is the same throughout the structure;
• the coating is not stated or is stated in general terms, without system, thickness and colour;
• elements do not fit the galvanizing bath or the transport, and this is only seen after fabrication;
• hollow elements have no holes for zinc to enter and leave, no drain holes and no hanging points;
• dimensions missing or ambiguous, unfinished joints, welds with no access, no agreement with adjacent elements, no design schemes;
• sheets of different revisions in one package with no note of which is valid;
• inspection and document requirements are not named and are sorted out only after the contract.

Each such item means a query and a pause before fabrication starts.

Checklist before sending

Go through the list before sending the package. If the answer to an item is «no», the third column says what this means for the fabricator.

How to send the package

Send the package by e-mail to info@polygonal.com.ua; empty items do no harm, we will clarify them during the calculation. The stages from request to shipping are described in the article How to order poles and masts.

If there are no KMD drawings yet, we prepare KM and KMD drawings: what they are and what goes into the set is covered in the articles What is KMD, KM drawings and KMD drawings; on design and fabrication see the pages Design and Steel fabrication. We fabricate steel structures to the customer’s drawings and do cutting, bending, welding, hot-dip galvanizing and powder coating. Erection is done by our partner construction company.

Standards and validity

Which standards apply to drawing up drawings and what they say about the specification, mass and scales is covered in the articles Drawing rules for KM and KMD and KM and KMD stages; they are not repeated here.

The notions of the execution specification, execution classes EXC1–EXC4, surface preparation grades P1–P3, tolerance classes, identification of products and the list of additional information the project must state (Table A.1) are given in DSTU EN 1090-2:2019 «Execution of steel structures and aluminium structures. Part 2: Technical requirements for steel structures» (cl. 4.1, 6.2, 6.10, Annex A; in force from 01.07.2020, replaced DSTU B EN 1090-2:2014). The execution class is determined by the project under Annex U of DBN V.2.6-198:2014 with Amendment No. 1.

The checklist in the article is a practical list; it does not replace the project and the contract. Requirements for documents, scope of inspection and coating are fixed in the contract; the bath dimensions and the thickness ratio are taken from our articles on galvanizing.