How Should You Select a Smart Lock for Industrial Sites?

A Practical Selection Guide Based on Three Years of Operating Experience at POSCO Pohang Steelworks

Introduction — Why I Wrote This

“We introduced smart padlocks, but they became unusable in just two months.”
That may sound like an exaggeration, but it actually happened.
From March 2022 to October 2024, FINEX Plant No. 3 at POSCO Pohang Steelworks operated a Smart ILS system using Bluetooth Low Energy (BLE)-based smart padlocks from NOKE in the United States. During that period, we encountered numerous problems that we had not anticipated, and this guide is based on those field experiences.
There are many types of Smart Locks, and specifications vary widely by manufacturer. If you choose based only on a catalog, you may face serious problems in actual field operation.
“What type of lock should be used in what kind of environment?”
This guide gives an honest answer based on real operating experience.

What You Need to Understand First — What Is Smart ILS?

Before going further, it is helpful to clarify a few terms.

ILS (Isolation Locking System) is a procedure used to isolate energy sources and lock them out during equipment inspection or maintenance work in order to secure safety. It may be understood as conceptually similar to LOTO (Lockout/Tagout).

Smart ILS adds digital technology to that process. Instead of relying on physical keys and paper-based records, it uses smart locking devices, mobile applications, and server systems to automatically record and manage the entire workflow.

A Smart ILS system is generally composed of five major elements.
◌ KMS (Key Management Server) handles lock registration and the issuance and retrieval of digital keys.
◌ ILSS (ILS Operation Server) serves as the brain of the system, managing user authority, work procedures, and operating status.
◌ Administrator Web Console is the central control interface where lock status and work progress can be monitored and managed in real time on a PC screen.
◌ Mobile App is the field tool used by workers and supervisors to control locks and process work requests and approvals.
◌ And at the front line of the site, connected to all of the above, is the Smart Lock itself.

In the end, the Smart Lock stands at the very front line of the entire system. No matter how well the servers and apps are built, if the lock in the field does not operate properly, the whole system fails. That is why Smart Lock selection matters.

Types of Smart Locks — See the Full Picture First

Smart Locks can generally be classified in three ways.

From the standpoint of installation environment, there are:
◌ padlocks for harsh environments, intended for sites with high temperature, heavy dust, and corrosive gases,
◌ padlocks for general industrial environments such as ordinary manufacturing and maintenance areas,
◌ and cabinet locks for equipment cabinets and security enclosures.

From the standpoint of operating method, there are:
◌ wireless BLE/NFC-based types,
◌ wired USB connection types,
◌ and externally powered types (battery-free design).

The advantages and disadvantages of each are explained later.
From the standpoint of ECD type, there are:
◌ P-ECD (Portable ECD), a portable device that supplies power to battery-free locks in the field,
◌ and S-ECD (Standalone ECD), a fixed control device that can operate locks even in special environments where carrying a smartphone is prohibited.

How Different Is an Industrial Site from a General Environment?

What happens if you take an electronic product designed for an office or commercial building and use it in a steel plant? In most cases, it will not last long.
To understand how harsh a heavy industrial environment such as POSCO Pohang Steelworks really is, it helps to look at five aspects.

Temperature — A Furnace in Summer, Below Freezing in Winter
Inside a steelworks, areas around blast furnaces, converters, and continuous casting lines can easily exceed 60°C. In contrast, outdoor work areas in winter can fall below freezing. Ordinary electronic parts cannot withstand such extreme temperature variation. In particular, energy storage components such as batteries and capacitors suffer rapid life reduction at high temperatures and poor performance at low temperatures. A Smart Lock should operate normally at least in the range of –30°C to +80°C.

Humidity and Dust — The Invisible Enemies
Steelworks contain many cooling water systems, steam facilities, and wastewater treatment facilities, so humidity is high and direct water splash is common. In addition, iron powder and fine metal dust are constantly present in raw material yards and steel production processes. When this dust accumulates on the surface of a lock and combines with moisture, it hardens. The shackle can become stuck to the body and may no longer open at all. This actually happened in the field.

Electromagnetic Interference (EMI) — The Enemy of Bluetooth and NFC
Large electric furnaces, arc welders, heavy motors, and transformers generate strong electromagnetic fields. These fields interfere with short-range wireless communication such as BLE and NFC. In steel plants filled with metal structures, wireless signals are frequently reflected or blocked, resulting in unstable communication. There are real cases where a smartphone was held directly against a lock and still could not connect.

Vibration and Impact — A Site That Never Stops Shaking
Continuous vibration from large presses, rollers, and conveyors weakens internal connections inside the lock. It is also not uncommon for locks to fall from height or get trapped between pieces of equipment.

Chemical Corrosion — It Rusts Without Being Seen
Strong acids and alkalis used in cleaning operations, salt-laden air at coastal steelworks, and hazardous gases such as hydrogen sulfide, sulfur dioxide, and carbon monoxide gradually corrode the lock. Even if the exterior still looks normal, the internal electronics may already be damaged.

Problems We Actually Experienced — Three Years of Operating BLE Padlocks

That is enough theory. Let us look at what actually happened.
During operation of BLE-based smart padlocks at FINEX Plant No. 3 in Pohang, three major problems repeatedly occurred.

Problem 1 — The Lock Became Unusable in Just Two Months
At the steelworks, iron dust, fine particles, and moisture combined to cause severe corrosion on the shackle or to make it adhere to the body in less than two months. The product had an IP66 ingress protection rating and was even fitted with a protective cover, yet in many cases fine dust and moisture still entered and corroded the electronics. One may think, “Isn’t IP66 enough?” But in an extreme environment with continuous exposure, we learned that the rating on paper does not always match actual durability.

Problem 2 — The Battery Drains Too Quickly
The BLE padlocks then in use operated on an internal CR2 battery. Because the field temperature fluctuated widely from –20°C to 80°C, battery performance dropped rapidly, requiring replacement every two to six months. On sites operating dozens or hundreds of locks, this became a major operational burden.
The bigger problem was that battery level was difficult to assess accurately. Due to the characteristics of primary batteries, the residual charge indication became unreliable as usage accumulated, so a lock might show that it was still acceptable and then suddenly discharge completely. If a lock suddenly stops responding during field work, that can directly lead to safety risk.

Problem 3 — Bluetooth Connection Is Too Slow
Because of the nature of Bluetooth, pairing between the smartphone and the lock took on average eight to ten seconds. In poor environments, it sometimes took more than thirty seconds. This is not merely inconvenient. In a site where multiple locks must be processed quickly, the entire work flow is delayed.
Around some equipment, the electromagnetic field generated during operation was so strong that even when the smartphone was held directly against the lock, connection failed completely.

Then What About an NFC-Based Battery-Free Padlock?

“If battery problems are the issue, what about a battery-free NFC lock?”
That is a reasonable question. At the end of 2022, we also conducted a trial operation of an NFC-based battery-free padlock at the same site.
In the NFC method, the 13.56 MHz radio field emitted from the smartphone induces current in the coil inside the lock, and that energy is used to operate the lock. In theory, it is attractive because it can be used semi-permanently without a battery.
However, the results in Pohang did not meet expectations.
The biggest problem was electromagnetic interference. Near large electric furnaces and arc welders, NFC signals were heavily disturbed, so authentication sometimes took 30 seconds to one minute or became impossible altogether.
Temperature was also a problem. In the NFC method, energy received from the smartphone is temporarily stored in an internal capacitor and then used. At high temperature, capacitor charging efficiency dropped, and in below-freezing conditions discharge performance deteriorated, resulting in cases where the lock would not open.
Signal reflection and blocking caused by metal structures, and internal component damage caused by vibration and dust, also appeared in the same way.
In conclusion, NFC-based battery-free padlocks show good performance in laboratory conditions or in general office and commercial environments, but in heavy industrial sites their limitations are still clear.
That said, NFC technology is evolving rapidly, so it should be noted that this evaluation reflects field testing conducted in 2022.

So How Should You Choose? — Selection Criteria by Site

Based on all of these experiences, the following are essential criteria that must be checked when selecting a Smart Lock.

1) Understand the Actual Site Environment First
What matters more than the catalog specification is the real condition of your site. You must specifically confirm the average, maximum, and minimum temperature, the concentration and composition of dust, whether there are nearby sources of strong electromagnetic fields, and whether water or chemicals may directly contact the lock.

2) Reduce Dependence on Batteries
Locks with built-in batteries become difficult to manage in environments with severe temperature variation because battery life becomes unpredictable. If possible, first consider externally powered battery-free designs or wired USB connection types. If a battery is unavoidable, the replacement cycle and monitoring method must be included in the operating plan before deployment.

3) Check the Compatibility Between the Communication Method and the Field Environment
BLE, NFC, and wired connection each have strengths and weaknesses. In environments with severe electromagnetic interference, it is difficult to avoid communication instability when using BLE or NFC. In such sites, a wired USB method is far more stable. On the other hand, in general manufacturing environments where mobility is high and the distance between facilities is large, BLE may be convenient.

4) Do Not Rely Only on the IP Rating — Verify Actual Durability in Use
Ingress protection ratings such as IP66 or IP67 are test results under defined conditions. As shown by the Pohang experience, when dust, moisture, and corrosion act together over a long period, actual durability may differ greatly from the certified rating. If possible, it is advisable to carry out a field trial under conditions similar to the actual site before deciding on full-scale deployment.

5) Check the Shackle Material and Surface Treatment
In most locks, the first part to fail is the shackle. Confirm whether it is made of high-strength boron steel with strong resistance to corrosion and impact, whether anti-corrosion treatment has been applied, and, if the site has concerns about spark generation, whether it includes an insulating cover.

6) Sites Where Smartphones Are Prohibited Require a Separate Plan
In areas where smartphones cannot be brought in, such as gas explosion hazard zones or security-controlled facilities, ordinary mobile app-based control is not possible. In such cases, a separate control device such as S-ECD (Standalone ECD) must be introduced together with the system. This point is often overlooked during planning, so it must be checked in advance.

Summary — Smart Lock Selection Checklist at a Glance

Closing Remarks

A single Smart Lock can become the last physical line of defense protecting a worker’s life.

Our three years at POSCO Pohang Steelworks taught us firsthand that no matter how good the overall system may be, it can become useless if the actual field environment is not properly reflected in the design and selection process. Field conditions come before catalog specifications. Pilot operation before deployment is the shortest path to reducing cost and risk.
Above all, please do not underestimate the fact that the choice of a single lock can be directly connected to human safety.

This guide is based on the operating experience of Jiwootech Co., Ltd.’s Smart ILS solution. Results may vary depending on site conditions, and professional consultation is recommended before deployment.