Source: Worksafe New Zealand
WorkSafe New Zealand has uncovered forged diesel‑tank certificates in use and is urging businesses to verify that their documentation is the real deal, in order to keep safe.
Between February 2017 and September 2023, Philip Mansfield turned legitimate certificates into convincing‑looking fakes using the names of real certifiers. Mr Mansfield, a tank installer who has never been an authorised compliance certifier himself, has now been sentenced in the Wellington District Court for making false documents.
The fraud unravelled in 2024, when a maintenance worker raised concerns about a diesel tank at the National Library site in Whanganui. An inspection revealed the compliance certificate was fake. From there, a wider probe by WorkSafe found six police stations also had false certificates for diesel tanks used to fuel their back-up power generators.
The forged certificates were for diesel tanks holding up to 7,500 litres. Without proper inspection, defects such as faulty pipework, inadequate containment, corrosion, or incorrect installation can go unnoticed. These can lead to serious incidents, particularly at sites that need to remain operational in emergencies.
WorkSafe’s Head of Authorisations and Advisory, Kate Morrison, says the case highlights the essential role certification plays in preventing fires, explosions, leaks, and environmental contamination.
“Certification is not paperwork for paperwork’s sake. It is the independent verification that systems for hazardous substances are designed, installed, and maintained safely. When someone forges certificates, they put workers, emergency services and the public directly in harm’s way.”
WorkSafe is reminding all businesses with hazardous substances installations to:
- verify certificates directly with the issuing compliance certifier or by checking the WorkSafe register
- contact WorkSafe if you have a concern
- ensure regular inspections and renewals are completed by authorised certifiers, as required under the Health and Safety at Work (Hazardous Substances) Regulations 2017.
WorkSafe says the case represents avoidable risk, not a regulatory technicality.
“Anyone operating a hazardous substances system must understand their responsibility to ensure the certification is real, current and issued by someone authorised to do the work,” says Kate Morrison.
“Diesel tanks of this scale need robust systems and regular oversight. The certification regime exists because failures can be catastrophic. If something doesn’t look right, check. That simple step is what uncovered these forgeries.”
Businesses can either check a certificate directly with the issuing certifier, or against WorkSafe’s official register.
WorkSafe has recently strengthened its compliance monitoring to give more confidence in how its permit systems are working. This helps WorkSafe better detect and respond to fraud, which undermines these systems and disadvantages people who follow the rules.
Check the register of compliance certifiers(external link)
Notify WorkSafe of a health and safety concern
Background
- Philip John Mansfield was sentenced at Wellington District Court on 2 April 2026.
- Judge Warburton imposed 5 months community detention.
- Mansfield was charged under section 256(2) of the Crimes Act 1961
- Made a false document, knowing it to be false, with the intent that it in any way be used or acted upon in New Zealand as genuine.
Media contact details
For more information you can contact our Media Team using our media request form. Alternatively:
Email: media@worksafe.govt.nz
