Accepting multi-sided poles: what is checked at the factory and on site

Where acceptance starts

Everything checked on site has to be agreed before fabrication: which drawings the pole is made to, which welds are inspected and by what method, which documents ship with the product. So the scope of inspection and the document list are best stated in the enquiry. The KM and KMD drawings used to check dimensions are prepared by us or sent by the customer: KM and KMD design.

The general inspection routine in production is covered in the article on quality control of steel structures. This one deals with what is specific to multi-sided poles: long sections with flanges, telescopic joints and a zinc coating.

In the shop: section geometry

Dimensions are checked against the drawing on every section and on the assembled product: length, section size, position and diameter of holes, squareness of the flanges to the shaft axis, straightness of the axis. A tape, a caliper, a square and templates are enough. A long section is laid on supports at one level for measuring, because it sags under its own weight.

For lighting poles the tolerances are given in the European standard EN 40-2: the axis deviates from a straight line by no more than 0.003 of the length, and the flange is within 1° of square to the axis. For power line poles and masts the limits come from the design or the technical specification. These figures can serve as a guide there too, but they become a requirement only when written into the design or the contract. More in the article on EN 40-2 dimensions and tolerances.

The telescopic joint is checked separately. Its length must equal the nominal one within the tolerance stated in the design documents, usually 10–12 % of the joint length. The marks between which the sections must seize are usually applied by the manufacturer; if there are none, the erectors apply their own following the assembly instruction.

In the shop: welds

All welds are inspected visually, including the longitudinal seam of the shaft and the flange welds. The inspector looks for cracks, undercut and lack of fusion at the surface, porosity, overlap, slag and spatter. Internal defects, namely cracks, lack of fusion and slag inclusions, are found by ultrasonic testing, which we carry out in the shop.

We do not carry out radiographic testing. If the design requires it, say so before the contract is signed. Cracks in welds are not allowed whatever their size: the defective section is gouged out to sound metal, filled with new weld metal and inspected again. The customer can state in the enquiry which welds to check and by which method. For the joints themselves see the article on weld types.

In the shop: holes, flanges and completeness

The most expensive mistake is a flange that does not fit the anchors. The hole in the flange is only slightly larger than the bolt, so the relative position of the holes matters, not only their diameter. The number of holes, their diameter and spacing are checked against the drawing of the anchor cage or foundation (anchor bolts and cages).

The cage is cast into the concrete in advance, so a mismatch with the flange found after that is very hard to fix. For this reason, if the cage ships with the pole, it is checked against the flange already in the shop.

Completeness is checked against the order specification: all sections, flanges, brackets, ladders and service platforms, lifting lugs on the sections, fasteners.

In the shop: zinc coating and marking

After galvanizing the thickness is measured with a magnetic gauge and the surface is inspected. The minimum depends on the steel thickness: for an article thicker than 6 mm it is 70 µm locally and 85 µm on average, for over 3 up to 6 mm it is 55 and 70 µm (DSTU EN ISO 1461:2024). The table and the measuring procedure are in the article on coating thickness.

Grounds for rejection are blisters, uncoated areas, sharp projections and thickness below the minimum. Darker or lighter areas, orange peel and stains from damp storage are not grounds, provided the thickness is in order. Uncoated areas up to 10 cm² are repaired if together they do not exceed 0.5 % of the surface; otherwise the article is galvanized again.

Marking is checked before dispatch: every section carries its mark from the drawing, and the telescopic joint carries the seizing mark. On site the pole is assembled in the right order by these.

On site: unloading and storage

On unloading every section is inspected: dents, a crushed end or flange, chipped zinc, scratches. Completeness is checked against the documents. Remarks are best recorded at once, with the place and nature of the damage: after erection it is almost impossible to prove where a section was damaged.

Sections are slung with flat textile slings or steel ropes passed through rubber-fabric sleeves. Bare ropes must not be used, they damage the zinc. A pad lies under the sling at the attachment point, and the sections are stacked on timber bearers.

If the poles will wait for erection for a long time, they are stored dry and ventilated: with spacers between articles, sloped so that water drains, raised off the ground and without shrink film. White deposit on zinc appears precisely from moisture without airflow, see the article on white rust.

On site: foundation, anchor bolts, section assembly

Before the lift the foundation is checked, not only the pole. Below-ground work must be complete, the foundation set out to level and pole axis, and the concrete must have reached the strength required by the design; in our erection recommendations this is not less than 50 %. Every anchor bolt is measured and the result entered in the as-built diagram. If a bolt is off, it is corrected before the pole arrives, rather than forcing the flange on site.

Assembly of sections with a telescopic joint starts with a clean, smooth surface in the joint zone. The sections are laid one after another on timber bearers levelled horizontally and pulled together under increasing load until relative movement stops. The recommended pulling load is not less than 10 t. The joint must seize within the marks.

If several jacks or hoists are used, the load is kept even: a skew and premature seizing of the sections are hard to correct.

On site: erection, tightening, verticality

The pole is slung not less than 500 mm above its centre of gravity. Once lifted, it is placed on the anchor bolts, aligned, and all nuts are fully tightened before the slings are released. Only then are the slings removed. A lock nut keeps the anchor nuts from backing off.

Verticality and plan position are checked against the design. The permissible deviation from vertical is set by the design, so we give no figure here. It is measured in two mutually perpendicular directions before the slings are removed: while the pole is still on the slings, it can be adjusted with the levelling nuts.

Bolted joints are checked for tightness. Heads and nuts sit tight on the surfaces and washers, and at least one full thread remains on the nut side. Erection bolts are tightened to not less than 15 kgf·m; quality is checked by the method of the project or of the manufacturer’s instructions; a practical technique is tapping with a 0.4 kg hammer (the bolt must not tremble or shift) and checking tightness of the joint with a 0.3 mm feeler gauge (a technique from the former DSTU B V.2.6-200:2014, withdrawn on 02.02.2026). On galvanized poles the nuts are tightened again after a week to make up for the zinc settling.

Erection is done by a licensed partner construction company under the works execution plan. Technical supervision is the customer’s: it checks the foundation, accuracy of assembly, locking of the nuts and the condition of the coating. The erection procedure is covered in the article on pole assembly and erection.

Typical remarks and what is done about them

A telling example is a base frame under a portal leg. By the drawing the clear internal dimension between the welded angles was to be 500 mm. Where the cross-piece stands it only just held 500, while higher up, where there is no cross-piece, the measurement gave 480 mm. The leg would not go into the frame, and when it was forced in with a jack, the weld tore. The fix is a wider cross-piece or channel sections in place of the angles.

The lesson is wider than this case: the dimension by which one part enters another is measured in several places along the length, not at one. This applies to flanges, anchor cages and sockets for shafts. The remaining remarks follow from the checks above.

Which documents to ask for with the product

The list of documents is agreed before fabrication starts. The usual requests are:

• mill certificates for the steel, or laboratory test reports;
• the KM or KMD drawings the pole is made to, and the erection diagram with the assembly instruction, especially for telescopic joints;
• results of the zinc coating thickness measurement, if agreed;
• weld inspection records in the agreed scope: visual and ultrasonic;
• on site: the as-built diagram of the anchors and the works execution plan with its technological cards.

Who is responsible for what

We prepare KM and KMD drawings, fabricate the poles and galvanize them: KM and KMD design, steel fabrication. A foundation design is done as a separate order for a separate fee; often we only pass the loads on to the foundation, and the customer designs it.

Erection is done by our partner construction company. If a pole is already standing and its condition is in doubt, a technical inspection can assess it.

Standards and validity

Steel poles are calculated and detailed under DBN V.2.6-198:2014 «Steel structures. Design standards» (in force; edition with Amendment No. 1). Requirements for the execution of steel structures, including geometric tolerances, welding, inspection and documentation, are in DSTU EN 1090-2:2019 «Execution of steel and aluminium structures. Part 2. Technical requirements for steel structures» (in force since 01.07.2020). The scope of inspection and the execution class are determined by the design. Requirements for the zinc coating are set by DSTU EN ISO 1461:2024 (in force since 12.01.2024).

Tolerances for lighting pole dimensions are given in the European standard EN 40-2. It is mentioned here only as a guide; check the validity of its national version separately. Listing a document here does not mean the product is certified: requirements for a particular order are fixed by the design and the contract, and the figures in this article should be checked against the current edition of the document named in the design.