What is TUV-AK-6 Certification


Thread Starter


Dear All,

In one of our system for offshore plant we need PLC which is certified for TUV AK-6. Can any one out here let me know what the TUV AK-6 stands for and what does it specify.

Is there any website which gives the detailed definition/information on the TUV AK-6 specification/certification.

Thanks for the help


H. shah
Here is data extracted from the "www.tuvasi.com":http://www.tuvasi.com website.

What are SIL levels?
The newly published international standard IEC 61508 ("Functional Safety of electrical/electronic/programmable electronic safety-related systems") defines four SIL levels (1 to 4). (SIL = Safety Integrity Level.) There is no direct conversion between the AK categories and SIL levels, but for example in a typical application AK 5 and AK 6 might correspond to SIL 3. Because IEC 61508 is new, the DIN standards are still in common use.

IEC 61508 is a generic standard, and can be applied to any industry that uses programmable systems for safety functions. The SIL levels from IEC 61508 are also used in (draft) IEC 61511 (for the Process industry).

What are "AK" and "RC" ratings?

German standard DIN V 19250 ("Basic Safety Evaluation of Measuring and Control Protective Equipment") defines eight "AK" classes (1 to 8). AK = Anforderungsklasse = Requirement Class (RC).
These ratings are used in DIN V VDE 0801 (for computers/PLC's), and more generally, in (draft) DIN 19251.
According to IEC 61508, AK6 corresponds to SIL3 (Safety Integrated Level 3).

Wolfgang Albert

david mertens

TUV is a German state controlled organisation established to verify technical installations ranging from ordinary cars to nuclear and chemical plants on safety issues.

The AK6 level is a safety level the logic controlling system of a plant (or part of a plant) has to fullful. The levels go from 1 to 8 with 8 being the most stringent safety requirement (I think nuclear plants fall under AK8). A good article on these issues can be found at: "www.iica.org.au/Members/hazsym97/risk.htm":http://www.iica.org.au/Members/hazsym97/risk.htm .
TUV AK6 is from German "Anfonderungsklasse". Newer concept defines the SIL (Safety Integrity Level).

This is clearly defined in the DIN 61508 or ANSI/ISA S84.01.

Deals with the requirements for safety.

try to find on the Web: 61508, Safety, "www.exida.com":http://www.exida.com

Manufacturers of Safety PLC's:
ICS Triplex
... and many more ....

Hope this helps

H.A. Soobrattee

TUV is an Organisation which certifies safety and shutdown systems as well as some electronics such as Computer Monitors.

AK-6 is a safety level designation for PLC and DCS systems. AK-6 being highest and AK-1 being lowest.

For PLC certified to AK-6 check out Quadlog system by Siemens-Moore at "www.moore-solutions.com":http://www.moore-solutions.com .

My company Alphatech Corporation Ltd. ( "[email protected]", mailto:[email protected] ) is distributor in Caribbean region.

Regards, H.A. Soobrattee
Dear All,
I am control system engineer and working in this field from last 16 years. Right now I am doing automation consulting (free lancing). I have used almost all TUV PLCs.

Basically TUV AK6 is guide lines of system configuration which are used for special application like burner management, ESD & fire & gas. In these application safety is very important which is taken care ny TUV guidelines.

There various classes in TUV like AK1, AK2 ... AK6. AK6 class means higest safety and availability.

TUV AK6 PLCs totally different from normal PLC. So we cannot make comparision between domestic PLC with TUV PLC. In this type of PLCs safety is most important so during every scan PLC is checking all the hardware so scan time for all TUV PLCs are around 150 msec. But if you take normal PLC example then it is 30msec etc.

As per my experience Honeywell has got best solution for TUV AK6 class specially for F&G application. As other PLC in the market does not meet 100% TUV AK6 requirement.

All the best and come back to me for more details if required.
Not exactly. AK 8 is the highest level defined. AK 6 is the highest level software based systems have been approved for.

Paul Gruhn, P.E., C.F.S.E.
Siemens, Houston, TX

Dennis Wright

I would be interested in why Shaner believes that the 'other' safety PLCs do not make the TUV AK6 specification?

As the senior validation engineer for ABB on the SC300E TMR system I have done a lot of work with both TUV's involved in the certification of safety
PLCs and I can ensure you that you either make the standard or you do not! All certified systems from all the manufacturers have to publish a safety manual, this defines the life cycle for the PLC, design, configuration, application, field I/O, operation, and decommissioning. TUV will also publish a report, this will state any limitations or restrictions in use and must be read in conjunction with the safety manual. So the fatter the report the greater the number of omissions in the safety manual and restrictions
imposed by TUV, and of course vice versa.

As for the 61508 standard, the amount of paperwork that must be submitted is awesome!

In my opinion the AK5/6 certification of DIN 801 is stricter for the hardware and the systems fault tolerance, but does not include the control loops only recommended configurations and operating procedures. While 61508 expands to
cover the whole plant, the SIL level for all safety control loops from input to output must be calculated and a safety case be produced, while the safety PLC only forms between <15% of the SIL calculation.


Dennis Wright

sorry about the long link!
Dear All,

Let me thank you all those who took pain to reply my earlier question "What is TUV-AK-6 Certification".

As far as my knowledge is, the GE fanuc's TUV AK-6 compliant PLC is TMR while other PLC's of make Yokogawa/ HIMA/ICS..etc are not TMR still they are TUV AK-6 approved.

Hence What I want to know is the basis/ criteria/ testing by which a PLC is said to be TUV AK-6 compliant.

If any one has any idea please let me know.

Thanks for the help


H. shah
Triplication is *NOT* a requirement for AK 6. A listing of the vendors, system, level of redundancy, certification level, date of approval, etc. can be found at both "www.tuvglobal.com":http://www.tuvglobal.com and "http://www.tuv-fs.com/plclist.htm":http://www.tuv-fs.com/plclist.htm .
The first URL is 'prettier', but second is easier to naviage and has info on the standards.

The requirements for the vendor are listed in a VERY long set of hardware and software requirements in DIN/VDE 0801 Appendix A.

The ICS-Triplex systems ARE TMR! I can only hope someone is not trying to convince you that GE's solution is the 'only' TMR!! They got into the TMR market > 10 years after the TMR leaders!!

Sorry Hitesh, but I think you're asking the wrong sort of questions!

Paul Gruhn, P.E., C.F.S.E.
Siemens, Houston, TX
Dear Mr Paul

Thanks for the reply. However I could not make out what's wrong in the question I am asking.

I am looking for the Basis and the procedure to obtain the TUV AK-6 compliance....I am not getting carried by the market information that's
why I have approached to this forum where the information is available without any ill intension.


Kiel-1, Larry


I'm not an expert at this but I think I can shed a little light on the subject. I don't know what a TUV AK-6 certification means but their is an independent testing agency in Germany that certifies PLCs to specific safety levels. Their web site is attached below but to tell you the truth it wasn't much help when I tried to find out what AK-6 is. Maybe you will have more luck.

When something has a TUV certificate it means that is has passed a specific set of testing requirements that the TUV people use to validate the equipment. If you need something TUV certified you are probably dealing with a control system that needs to be either fail safe (very reliable with redundancy designed in) or you have a safety issue that you are trying to minimize. I know that GE Fanuc and Siemens both have TUV certified PLCs, but I don't know to what certification level. You might be able to find out at their web site. I'm sure other PLC manufacturers also have TUV certifications.


I hope this gets you started.

Larry Kiel
As anyone Interfaced a SIL rated Safety DCS to existing AK field Instrumentation or performed Self Certification?