Every new piece of equipment headed for an oil and gas installation faces the same question sooner or later. How mature is this technology, and what evidence backs that up? The industry answers it with technology readiness levels, or TRLs, and with formal qualification processes built around them.
Digital field worker programs bring that question to mobile devices. When a site moves from radios and paper to iPhones and iPads in Zone 1, HSE and engineering teams need to know where those devices sit on the TRL scale and how much qualification work they carry. Whether a team calls them intrinsically safe phones or explosion-proof devices, the answer for a certified iPhone is the same. It sits at the mature end of the scale, and most of the evidence already exists.
A technology readiness level describes how far a technology has progressed, from an idea on paper to a system proven in real operation. The scale originated at NASA, and the version most people know runs from TRL 1, where basic principles have been observed, to TRL 9, where the actual system has been proven in its operational environment. NASA's technology readiness level definitions remain the common reference.
Oil and gas adapted the idea for subsea and offshore equipment, where failures are costly and retrieval is difficult. API 17N, the American Petroleum Institute's recommended practice on subsea reliability, technical risk and integrity management, uses a 0 to 7 scale instead. Its top level, TRL 7 or "field proven", describes a production unit installed and operating for more than three years with acceptable reliability.
Because both scales are in everyday use, it pays to state which one you mean. The table below shows how they line up.
| Maturity stage | TRL 1-9 scale (NASA, EU) | API 17N 0-7 scale |
|---|---|---|
| Concept and paper study | TRL 1-2 | TRL 0-1 |
| Validated concept and laboratory testing | TRL 3-4 | TRL 2-3 |
| Prototype tested in a relevant environment | TRL 5-6 | TRL 4 |
| System integrated, installed and qualified | TRL 7-8 | TRL 5-6 |
| System proven in operation | TRL 9 | TRL 7 |
The alignment in the middle rows is approximate, since each scale defines its steps differently. The end points match, though. TRL 9 on the general scale and TRL 7 on the API scale both describe a system with a proven record in field operation.
TRL describes where a technology stands. Technology qualification is the process of showing that it is fit for a specific purpose, and in oil and gas the main reference is DNV-RP-A203 Technology qualification. The process starts by defining what the technology must do, then identifies how it could fail, and finally gathers evidence that each failure mode is under control. API 17N includes a comparable annex on new technology qualification for subsea equipment.
Both frameworks concentrate on the unknown. DNV-RP-A203 is intended for technologies "not covered by existing, validated requirements" where failure poses a risk to life, property or the environment. It sorts each technology by how proven it is and how familiar its application is, and the qualification effort grows with the degree of novelty.
That is why qualification work tends to focus on new subsea processing equipment, autonomous inspection robots and machine learning systems for condition monitoring. Emerging autonomy and AI systems typically enter the process in the middle of the TRL scale, as prototypes and pilots, and need a structured body of evidence before operators can rely on them. For a neutral overview of both frameworks, see our explainer on DNV-RP-A203 and API 17N.
DNV-RP-A203 also makes a point that matters for mobile devices. Proven technology moved into a changed environment may still need qualifying. A consumer smartphone on a process deck fits that description, so the useful question is whether the new environment is already governed by an established standard.
Start with the device itself. Apple has produced a new iPhone every year since 2007, and each model builds on nearly two decades of mass production, design verification and daily operation in the hands of consumers and enterprises. On the general scale, that places the base device at TRL 9, an actual system proven in its operational environment.
The software stack is equally mature. Current iPhones run standard iOS, receive Apple updates for five to six years, and enroll in Apple Business Manager and established MDM platforms such as Microsoft Intune and Jamf. For a field worker program, the operating system, update process and device management are the same proven tools IT already runs across the rest of the business.
The same applies to the features field teams depend on. The 48 MP camera system and LiDAR scanner on the iPhone 17 Pro Max are production hardware used daily for photography and 3D scanning worldwide, and they translate directly into inspection photos, measurements and remote support in the field. Taking that proven hardware into Zone 1 is where the enclosure comes in.
What enters the hazardous area is a system, an unmodified iPhone or iPad inside an explosion-proof enclosure. The certification covers that complete assembly, case and device together, so the assembly is what should be assessed.
Explosion protection comes from flameproof design, Ex d, one of the longest-established protection concepts in hazardous areas. A flameproof enclosure accepts that ignition could occur inside it. It is built to withstand the pressure of an internal explosion, and its flamepaths cool escaping gases to stop flame passing to the surrounding atmosphere. Intrinsic safety works the other way, by limiting the energy available for ignition, and our article on intrinsically safe vs explosion-proof phones covers the difference in detail.
Ex certification is precisely the kind of existing, validated requirement DNV-RP-A203 refers to. Each enclosure is assessed by an independent certification body against the IEC and EN 60079 series. The Xshielder iPhone 17 Pro Max, for example, holds ATEX certificate FIDI 26 ATEX 0016X and IECEx certificate IECEx FIDI 26.0016X, with the marking II 2G Ex db IIC T6 Gb for gas and II 2D Ex tb IIIC T80°C Db for dust. Anyone can verify an IECEx certificate in the public IECEx certificate database.
Certification also extends to how the product is made. Xshielder holds a Quality Assurance Notification (DNV 24 ATEX 35423Q) issued by DNV as notified body, an IECEx Quality Assessment Report, and an ISO 9001:2015 quality management system certified by DNV. Certificates and declarations for every model are published on the Xshielder downloads page, and exknowledge's guide to Ex certification explains how these documents fit together.
In qualification terms, these documents are third-party evidence that the risk introduced by the new environment, ignition of an explosive atmosphere, has been assessed against an established standard by an independent body.
The combination is also in routine use. Xshielder devices work on producing offshore and onshore assets with several major operators on the Norwegian Continental Shelf, and more than 4,500 Ex-certified devices have been delivered worldwide. Our field deployment case study follows one North Sea rollout from pilot to daily use. The team behind the enclosures has designed Zone 1 smartphones since 2014.
On the general 1 to 9 scale, a certified assembly in routine production use meets the TRL 9 definition. API 17N sets a stricter, time-based bar written for subsea hardware that cannot easily be retrieved, and each new iPhone generation receives its own certificate, so every model builds its individual service record from launch. The protection concept, design approach, certification route and manufacturing system carry over from one generation to the next, and that continuity keeps the qualification burden low.
A certified device settles the hardware question. A digital field worker program still has other parts that deserve the same structured attention, and this is where qualification effort is best spent.
Connectivity is usually the biggest item. Wi-Fi, private LTE or 5G coverage across process areas, performance among steel structures, and radio approvals in each country of use all need checking. Xshielder maintains a country-by-country list of telecom approvals to help with the last of these.
Software and data come next. Field apps, integrations with maintenance and permit-to-work systems, and any analytics or AI models behind them may be genuinely new, and some will meet DNV-RP-A203's definition of novel technology. MDM configuration also matters, for example deciding whether devices should be camera-only or app-restricted inside the zone, and Xshielder provides lockdown guides for that purpose.
Procedures and people complete the picture. Pre-use visual inspection, charging and storage routines, accessories such as Ex-certified Bluetooth headsets, and user training all belong in the rollout plan. Xshielder publishes a visual inspection checklist for each model to support this, and our 2026 guide to intrinsically safe and explosion-proof mobile devices covers device selection in more depth. These topics also come up regularly at our Digital Field Worker event.
The pattern is consistent. The technology qualification burden is low where a rollout uses certified commercial off-the-shelf devices, and higher wherever it introduces new software, new integrations or new infrastructure.
If your digital field worker program needs Zone 1 devices that arrive with their qualification evidence in place, explore the Xshielder iPhone 17 Pro Max, the iPhone 17 and the iPad Pro 11". Get in touch for certificates, references and pricing from your local partner.
TRL 9 means the actual system has been proven in its operational environment. For hazardous-area equipment, that environment includes the classified zone, so the protection concept must also be certified for that zone.
DNV-RP-A203 treats proven technology in a changed environment as a candidate for qualification, and for an iPhone in Zone 1 that environmental risk is covered by ATEX and IECEx certification against the IEC 60079 standards. Both the device and its protection concept therefore rest on established, validated requirements.
The closest equivalent is API 17N TRL 7, "field proven", which describes a production unit installed and operating for more than three years with acceptable reliability.
Emerging autonomy and AI systems for offshore use typically sit in the middle of the TRL scale, at prototype and pilot stages. That is why they go through formal technology qualification before wider deployment.
TRL is a snapshot of how mature a technology is, while technology qualification is the process of gathering evidence that it will meet its requirements in a specific application. A high TRL reduces the qualification work needed for that application.
Look for an ATEX EU-type examination certificate and an IECEx certificate of conformity covering the complete enclosure and device, with a marking such as II 2G Ex db IIC T6 Gb. Production should be backed by a Quality Assurance Notification and an IECEx Quality Assessment Report.