KEY DIFFUSION LTD is a licensed and notified body with identification number NB 2574, with a scope, in accordance with the published in NANDO European Register, namely – performing conformity assessment activities, exceptional checks, intermediate inspections, periodic inspections, reassessment of conformity of transportable pressure equipment for substances of class 2 (with the exception of acetylene), as specified in Section 6 of ADR, RID and AND, in accordance with the provisions of Directive 2010/35/EC and the Ordinance on the material requirements and assessment of the conformity of transportable pressure equipment of the following types:

-          Cylinders, tubes, pressure drums;

-          Closed cryogenic receptacles;

-          Cylinder racks/bundles (batteries/sections and batteries/tubes);

-          Battery vehicles;

-          Containers of type MEGC;

-          Tanks;

-           and their components (valves) for transporting substances of class 2 according to  ADR/RID/ADN with the exception of those for acetylene.


Accredited control body of type A to KEY DIFFUSION LTD controls the transportable pressure equipment in the range according to the certificate of accreditation from EA BAS reg. №265OKA and its annex.


Types of testings/inspections:

  1. External and internal visual inspection – VT method.
  2. Testing the air tightness, density/thickness – LT method.
  3. Testing the strength limit by hydrostatic test upon action of internal pressure.
  4. Strength test by cyclical testing.
  5. Inspection for determining the cubical dilatation by hydraulic test method.
  6. Inspection by bending test.
  7. Inspection by tensile testing.
  8. Inspection for determining the spontaneous ignition temperature of the material in an oxygen environment.
  9. Inspection for examining the hardness of the material by the hardness test method of Brinell.
  10. Durability test by cyclical opening and closing of a valve under working pressure.
  11. Ultrasonic testing, determination of type, size and location of discontinuity / imperfections by UT method.
  12. Checking and setting the safety valves.
  13. Checking, marking.
  14. Control of geometrical dimensions by controlling the deviation from circularity, mean diameter, straightnes and verticality - through measurements and mathematical calculations.
  15. Inspecting wall thickness by ultrasonic test method.
  16. Inspecting cylinders’ bottom by thickness measurements and visual control (only for cylinders made of pipe blanks).
  17. Inspecting air tightness under cyclic load.
  18. Check for existence of transition resistance by measuring the conductance between tank elements or cylinder battery vehicle and the chassis / platform on which they are fitted, as well as of their output terminal for grounding.
  19. Inspection by the impact energy test of Charpy.
  20. Inspection of welded joints, determination of type, size and location of discontinuity / imperfections through the RT method.
  21. Inspecting the servicing tank equipment for carriage of substances of Class 2 of ADR.
  22. Inspection of the structure, components and operational equipment, check for the availability and condition of the entire equipment and all servicing facilities of the tank. Checking the correctness of the calculations for sizing the relief valves and construction.
  23. Checking the volume – capacity of the vessel by measuring/determining the water capacity and maximum filling volume.
  24. Inspecting the protective cladding / insulation coatings of a tank through the spark testing method.
  25. Magnetic particle inspection method, type, size and location of discontinuity / imperfections through the МТ method.
  26. Testing the compatibility of the material with the gas content by an auto-ignition test in an oxygen atmosphere.


KEY DIFFUSION LTD is a licensed authority for Technical Surveillance of the following types of High-risk equipment:

1. Stationary mounted cylinders for storage of liquefied, compressed or dissolved under pressure gases.

2. Gas pipelines, gas installations, gas-regulating units, fuel installations, cylinder installations, gas appliances and other gas equipment in administrative, residential and public buildings and sites.


1. Carries out Technical Surveillance of the abovementioned High Risk Equipment / HRE /.
2. Keeps direct connection with SAMTS as it keeps track of all changes in requirements and regulatory documents.
3. Plans and organizes the overall activities aimed at implementing the Technical Inspection of HRE and keeps register of these activities.
4. Provides consultancy and advises on issues arising in relation to the surveillance of HRE.
5. Advises HRE users on how to improve safe working conditions. Cooperates in organizing trainings for certification, qualification, requalification and in verifying the knowledge and competency of the managerial and executive personnel to operate with HRE, according to the established in the regulatory documents procedures.
6. Assists HRE users with:
• provisioning to the companies of the minimum required regulatory framework and complying with the applicable requirements (Law on Technical Requirements for Products, Ordinances concerning HRE, Rules, etc.).
• provisioning the “Inspectorial Books” and other documents necessary for the HRE files (for HRE registered in their names).
• having available all required operational instructions on safe and proper work with HRE, complying therewith by the staff and persons responsible for safe operation with HRE in all companies.





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