DNV 2.7-1 (DNV-ST-E271) Inspection: Intervals, Certificates, and Who Can Sign

Two clocks run on every certified offshore container. The container gets a visual inspection at least every 12 months and NDT of its pad eyes at least every 48, and the lifting set gets a visual every 12 months with NDT or a load test of its components every 48. Each inspection ends with a suffix stamped on the inspection plate or the sling tag: V for visual, VN for NDT plus visual, T when a load test was done as well. Miss the annual inspection and the container certificate lapses, and the standard's own guidance is that a container with less than 30 days of currency should not be shipped offshore.

What DNV-ST-E271 covers, and why everyone still says 2.7-1

DNV-ST-E271 is DNV's standard for offshore containers: portable units of up to 25,000 kg gross mass, with an outer frame and pad eyes, built for repeated transport in open seas to, from and between installations and ships. That takes in freight containers, service containers (workshops, laboratories, generator and pump units), waste skips and offshore tank containers. The standard covers design, materials, prototype and production testing, marking, plating and periodic inspection of the container and of the lifting set that is permanently fitted to it. IMO circular MSC/Circ.860 is the international guideline behind it, and coastal states accept DNV 2.7-1 certification as the way to meet that circular.

The name has changed twice and the number has stuck. Det Norske Veritas published Standard for Certification 2.7-1 in the 1990s. The August 2017 rewrite became DNVGL-ST-E271 after the DNV GL merger, and the 2021 rebrand made it DNV-ST-E271. The current edition is dated March 2023, amended December 2024. Every edition keeps "2.7-1" in its title, the plates and tags still read DNV 2.7-1, and so do the search queries.

The container schedule

Section 9 puts containers on the schedule below. When a lifting test is required, the NDT and the thorough visual examination both happen after it. The inspector may ask for more, including dismantling, and national authorities may require more frequent inspection.

"Substantial" means any repair or alteration that, in the surveyor's opinion, affects the primary structure or anything that contributes directly to its integrity. A container that has been rebuilt, repaired with different materials or sections, or re-rated has to be re-approved, may need new prototype tests, and gets a new certificate. The old one is marked "Deleted" and attached to the new one.

The visual inspection covers the exterior and the interior without cargo, with the container lifted or supported so the underside can be seen:

• markings and plates, against the standard and other applicable regulations
• welds in the primary structure, for visible defects
• pad eyes and lashing points, for distortion, mechanical damage or any sign of distress or overload
• the structure, for corrosion, mechanical damage or injurious deformation, with the base structure and other load-bearing parts first
• doors, frames, seals, hinges and locks, operated to check they work without undue force
• the floor, for deformation or distress, with drain holes clear of debris
• fork pockets, inspected inside, which is where corrosion and fork-lift damage hide

NDT of the pad eyes follows the production NDT requirements. Eddy current testing is accepted at periodic inspections because it works through sound paint; if it shows an indication, the paint comes off and the weld is tested by the conventional method against the production acceptance criteria. Eddy current operators need level 2 or 3 certification under EN ISO 9712 or an equivalent scheme.

The inspection plate records the result. It carries the owner's container number, the owner's name and the date of the last inspection, with room for at least nine entries, and it must not show the date of the next inspection. At each inspection the plate is marked with the date, the inspector's mark and the suffix from the table. Users treat the plate as prima facie evidence of certification status, which is why the 30-day currency rule of thumb exists.

The lifting set schedule

The lifting set is the chain or wire rope sling, with its master link assembly and shackles, fitted to the container and normally only removed for replacement. It runs on its own schedule, inspected at intervals not exceeding one year.

The chain leg load test is 2 × the WLL of a single leg rated to EN 818-4, within 2 percent, applied without shock and held for at least 2.5 minutes before anything is measured. NDT of components is magnetic particle testing to the production requirements. Inspection of the slings themselves follows EN 818-6 for chain and EN 13414-2 for wire rope. Shackles that are not assembly secured can be inspected on their own; assembly-secured shackles are inspected as part of the sling.

On completion, the inspector checks the tag marking is still complete, then marks column 1 on the back of the tag with the date, the inspector's mark and the suffix. If shackles were replaced, column 2 (the shackle identification) is revised or the tag is replaced.

In the UK sector LOLER applies offshore, the lifting set is a lifting accessory, and the 6-month thorough examination runs alongside the DNV schedule. In Australia the test houses that assemble and test these slings work under NATA accreditation to ISO/IEC 17025 and test wire rope slings to AS 1666 as well as the DNV requirements.

What makes a lifting set a DNV lifting set

Approval. Only lifting sets approved by DNV may be used on certified containers. Shackles, chain, links (master links, master link assemblies, intermediate and end links) and couplings must be type approved. DNV audits the manufacturer before issuing a type approval and regularly afterwards to keep it. Wire rope, ferrules and thimbles do not need type approval. A sling manufacturer that holds a type approval issues its own product certificate for the assembled sling; where no type approved product exists, DNV can issue a product certificate for an individual product or a batch. That is why a sling certificate lists a type approval number against the master link and each shackle, and a batch number against the rope and the ferrules.

Design. Slings are rated for their intended angle. Four-leg slings are always rated as three-leg slings. The leg angle to the vertical is normally 45 degrees and may be smaller, never larger. The minimum WLL of the set comes from a table that multiplies the container rating by an enhancement factor for the dynamics of offshore lifting: the factor is highest for light containers, the floor is 7.00 t for anything rated up to 2,000 kg, and a 25,000 kg container needs a set rated at 27.59 t. The same enhanced figure sizes every component, and each shackle on a four-leg set needs a WLL of at least that figure divided by 3 × cos 45°. A 10,000 kg container therefore needs a lifting set of at least 15.01 t and shackles of roughly 7.1 t each. The master link should reach down to no more than 1.3 m above the container base when the set hangs over the long side, and an extra top leg with a ring or link is often advisable to make hooking on easier.

Marking. The sling carries a metal identification tag permanently attached to the top assembly: round for wire rope slings, eight-sided for grade 8 chain slings, with characters at least 4 mm high. It shows the CE mark where applicable, the reference DNV 2.7-1, the certificate number and unique sling identification, the number of legs, the diameter of the chain or rope including any top leg, the WLL, the maximum leg angle, and the identification number of each shackle. Shackles are stamped with a unique identification using low-stress stamps, away from the highest-stressed areas. Where two 2-leg slings are used together as a 4-leg set, both are marked as 4-leg slings.

What the sling certificate must show

A sling certificate issued under Section 8 contains at least:

• the manufacturer's name, mark and location
• the date of issue
• the sling certificate number
• a reference to the DNV type approval certificate where relevant
• a description of the sling with its unique identification number or mark, and the identification mark of each component; where new components were fitted before re-certification, a reference to the previous certificate number and to the new components' marks
• the nominal size and length of the sling
• the WLL, together with the design angle to the vertical for multi-leg slings
• the date of manufacture or re-certification
• confirmation that the sling was designed, manufactured and tested to the standard
• the signature of the authorised DNV surveyor, or of the manufacturer when the certificate is issued under a DNV type approval

Wire rope slings also state the grade of the rope and terminal fittings and the product standard the sling conforms to; chain slings state the grade mark and standard, and assembly-secured slings cross-reference the shackle certificates. Component certificates for chain, shackles, links and couplings carry a parallel list, including the material certificates and the test results from the product standard.

Two details catch people out. The WLL on the certificate and the tag is the maximum rating of a container the sling may be used on at the given angle, which is not necessarily the gross mass of the container it is fitted to. And the sling certificate numbers are normally recorded on the DNV container certificate with the sling certificates attached, unless the owner runs a system that tracks each container and its lifting set.

What the periodic inspection report must show

When the container and its lifting set are fit for service, the inspector issues an inspection report. Separate reports are allowed for the container, the lifting set and any shackles inspected on their own. The report is attached to the container certificate or filed in the as-built dossier, and shows at least:

1. the container or lifting set identification, including the owner's container number
2. the owner's name, or the delegated nominee
3. the certificate number
4. the date and number of the preceding certificate of examination, who issued it and their employer
5. the total gross mass applicable to the all-point lifting test and the method of test, where relevant
6. details of any NDE carried out
7. a statement that the container or lifting set was thoroughly examined and that the particulars are correct
8. a reference to any report issued to the owner as a result of the inspection
9. confirmation that the inspection plate or lifting set tag was marked
10. the date of inspection, and the date of the report if different
11. the DNV mark and the signature and unique identification mark of the inspector

Item 4 is the one most in-house forms miss. Each report has to point back to the previous one, which means the inspection body needs the asset's history in front of it as well as this visit's findings.

Who can inspect, and who is responsible

The owner, or an appointed representative, is responsible for keeping each container's certification current, arranging the periodic inspections, recording substantial repairs, modifications and changes of identification, and keeping records that give traceability. A container that has gone past its inspection date while idle, or while sitting on an installation, should be inspected before it is used again.

Periodic inspection may be carried out by DNV or by other inspection bodies recognised by the national authorities, which should normally meet the requirements for a type B inspection body under ISO/IEC 17020 or an equivalent standard. Major repairs or modifications that may alter the certificate must be approved by DNV. Offshore tank containers certified for dangerous goods under the IMDG Code are a special case: they get 5-yearly inspections with an intermediate inspection at 2.5 years, covering the tank, its fittings, the frame, the lifting set and the plates, and only DNV or another authorised certifying body can do them.

DNV 2.7-1, 2.7-3, EN 12079 and ISO 10855

DNV's offshore container governance unit published a memo in October 2023 because manufacturers had been trying to certify box-shaped cargo units under E273 to avoid the frame, pad eye and testing requirements of E271. DNV's position is that a unit of 25,000 kg or less with an external structural framework, lifted offshore more than once, falls under E271 by default. The design classes in E273 are operational limits for units that are portable offshore units, and cannot be used to opt out of E271.

Where Core fits

If you assemble, test or inspect DNV lifting sets for customers, the standard turns into a data problem: a type approval number and a batch number for every component, a proof load for every leg, two different certificates for the same asset (the Certificate of Test & Examination at manufacture, then the Certificate of Inspection at each 12 or 48-month visit), NDT reports that have to attach to the right sling, and a report that has to cite the previous one. Core holds the lifting set as an asset with those component attributes on it, renders both certificates from your own Word template, keeps the NDT certificates and anomaly reports on the same history, and gives the container owner a portal with the as-built dossier.

Certex Lifting's NATA-accredited test laboratories issue their DNV-ST-E271 and DNV-ST-E273 certificates from Core, with the component traceability lines drawn from the asset record. Proofload's DNV-ST-E271 load test certificate is produced in Core, and DNV reviewed that certificate and accepted it for load tests under the standard. The DNV offshore container certification software page shows the workflow and a sample certificate, the free lifting set inspection record covers the Section 9 schedule on paper, and you can see it on your own workflow.

Sources

• DNV, DNV-ST-E271 2.7-1 Offshore containers (edition 2023-03, amended 2024-12)
• DNV, DNV-ST-E273 2.7-3 Portable offshore units
• DNV offshore container governance unit, memo 2023-03: Certification of offshore containers (DNV-ST-E271) and portable offshore units (DNV-ST-E273), 24 October 2023
• DNV, Verification and certification of containers and transport units
• Wikipedia, DNVGL-ST-E271
• LRQA, Ten years on: ISO 10855 for offshore containers released
• BSI, ISO 10855-3 Offshore containers and associated lifting sets. Part 3: Periodic inspection, examination and testing