What Does T9 Certificate (Certificate of Conformity for Vehicles Carrying Hazardous Material) Means? How Does the Process of Inspection and Certification Works? 
T-9 is a certification (ADR Certification) is prepared by the authorized institutions to confirm that the vehicle is eligible to transport hazardous goods. 
T9 Certificate is a Certificate which Shows the Vehicle Carrying Hazardous Material and the Tank Carried by the Vehicle Satisfy the Conditions of "ADR Chapter 9”. According to the ADR regulations, T9 Certificate can be given by the Authorized Institute at the Country where the Vehicle has been Registered. (Since January 2014 TSE is the Authorized Instıtute in Turkey.) 
"ADR Chapter 9” questioned the conformity of the mechanical connection points, chassis, tank, electricity and brakes of the moving parts according to the statute. 
T9 certificate prepared to the name of the company. The validity of the certificate is 1 (one) year and after the controls made by TSE, the certificate may be renewed or cancelled. 
In the Inspection Institutions which are authorized by TSE, tankers carrying hazardous material (LPG, JET A1, Fuel Oil, Chemicals etc.) should be implemented to the intermediate inspection in every 3(three) years and Periodic Inspection in every 6(six) years (in case of any modifications the exceptional inspection should be implemented), applicants can get the T9 certificate after the approval of the inspection. 
Necessary Documents for T9 Inspection, Intermediate Examination and Periodic Examination: 
   • Tank Registration* / π Certificate of the Tank / ADR Certificate
   • Gas Free Certificate
   • ADR Certificate of the Prime Mover
   • License (Registration and Traffic Certificate)
   • Company Signatory Circular
   • Conformity Certificate of Chassis Manufacturer (Ece R105)
* Content of Tank Registry:
   • Copy of Design Approval Certificate
   • Technical Drawings of the Inspected Tank
   • First Inspection Certificate / First Examination Documents of the Tank / Certificate of the Previous Examination. 
(First Inspection Certificate and Documents are necessary if the Periodic Inspection applied to the tank. If the Periodic Inspection applied to the tank earlier, the documents and certificates are required also.) 
   • Tank License Copy
   • Certificates and the list of the equipment used for the tank inspected and equipment will be used during the inspection.
   • Certificates and the list of the equipment used for the inspected tank
   • Reports of the test and inspections applied to the tank.
   • Record of the modifications and repair on the tank.(If the inspection applied after modifications, there should be modification report taken from the approved modification institute.)
As well as the documents required in order to get T9 Certificate, the intermediate inspections and the periodic inspections of the tank should be applied on time. Periodic Inspection should be applied for the tanks with expired intermediate inspection dates. If the inspection dates expired or inspections are not applied by the authorized inspection authorities (i.e.; KARBONSAN) since January 2014, just before the T9 certificate application they should apply to the authorized inspection authorities (i.e.; KARBONSAN) in order to complete the missing inspections.
What are the features of the vehicles with T9 certificate (Certified for Carrying Hazardous Material)?
It is a vehicle manufactured and approved by the authorized institute in order to carry and transport hazardous material. 
The vehicle with T9 certification, owns a special design, material and equipment according to the hazardous material which is carried by the vehicle itself. The superstructure of the tank or truck / chassis under the tank and the prime mover matched with the ADR semi-trailer should have Type Approval according to the ADR regulations. 
What are ECE R105 Regulation and 98/91/AT instructions? Why needed?
ECE R105 Regulation and 98/91/AT instructions describes the approval conditions and questions the mechanical, electricity and brake connections and their materials of the vehicles designed with the purpose of carrying hazardous material.
The vehicle and the chassis which are designed to carry hazardous material should have Type Approval according to ECE R105 Regulation and 98/91/AT instructions. ECE R 111 regulation should be obtained for the vehicles and chassis carrying tank with the test pressure below 4 bars.