Corrugated steel culvert pipe, aprons, end sections, coupling bands, special fittings, and associated hardware shall meet the requirements of Specification 4141 and Standard Road Plans.


Coated corrugated steel pipe shall meet the requirements of Article 4141.02 of the Specifications.


Approved sources are listed in the Materials Approved Products Listing Enterprise (MAPLE).



Metal will be accepted after the sheet manufacturer certified analysis and manufacturer guarantee have been reviewed by the Central Construction and Materials Office and accepted. A list of accepted brands of metal is contained in Appendix A.


Materials (sheet metal) used to fabricate corrugated pipe, end sections, aprons, coupling bands, special fittings, shall meet the requirements of IM 107, Group 2, Buy America.



Fabricator approval will be based on information supplied by the fabricator and an inspection of the pipe plants which are located within the state of Iowa. The fabricator shall submit the request for approval to the Central Construction and Materials Office, Iowa, and include the following information:


1.   Brands of metal to be used

2.   Diameters and corrugation size of pipe to be furnished

3.   Fabrication methods used

4.   Coupling devices furnished

5.   A copy of a typical invoice or bill of lading containing the certification statement of compliance as outlined in this IM

6.    Quality Control Plan/Program

7.    Qualified QC Personnel

8.    Plant approval (equipment, machinery, etc.)

9.    Audit results from the National Transportation Product Evaluation Program (NTPEP) are required for the corrugated metal pipe plants. 



Processes used to complete joints for Corrugated Metal Pipe must be acceptable and approved to the (AWS) American Welding Society and Iowa Standard Specifications.


A Welding Procedure Specification (WPS) for each process, that may be used, shall be approved by Office of Construction and Materials and must be nearby and accessible for the welders and welding operators at all times for the process that is being used.


Quality Control procedure -

·         Welder’s certification will be at the discretion of the designated Quality Control (QC) Manager for the plant and will include testing established to show verification the welder maintains the knowledge and ability to produce satisfactory welds.

·         The QC Manager shall maintain a list of all the qualified shop welders and each process they are qualified for. A continuity Log will be kept verifying no welder has gone more than a six-month period without performing one of the processes of welding.

·         The QC Manager is responsible for ensuring all fabrication and welding performed in the completion of the Corrugated Metal Pipe is completed in compliance with the Iowa Department of Transportation Specifications




·         Brand’s Name

·         Manufacturer’s Name

·         Sheet thickness, gage, and grade

·         AASHTO Designation

·         Heat number and coating lot number


Note:  Marking shall be applied by a permanent method.  The identification shall appear on the outside of the pipe. Stamping shall be placed at the end of the pipe or end section and on the top of the corrugation 6”-12” from the end.  The printed permanent ink shall be legible and not less than ˝” in size.



The pipe fabricator shall furnish an identification list, invoice or bill of lading for each shipment to an Iowa project or shipment to an intermediate distributor intended for use in Iowa. It shall list the project number, quantities and description of fabricated materials, corrugation size, and thickness of metal used for each pipe size shipped, and a certification statement of compliance with Iowa DOT Specifications. An authorized representative of the company shall sign the certificate of compliance.


The certificate of compliance shall be stated as follows:




The material covered by this certificate of compliance was manufactured in conformity with Iowa Department of Transportation Specifications Section 4141. Based on mill certificates and quality control testing, it is certified that representative samples of the listed materials have been tested in accordance with these specifications and that the results meet the requirements. (Material description and shipping destination are as shown.)  We also certify that all steel used meets the requirements of IM 107, Buy America



One copy of the document described above shall be furnished to the Project Engineer.  Copies of this original document shall be furnished as described above along with the invoice or bill of lading when shipments are made to a project from a distributor.


The fabricator or the intermediate distributor shall also provide summary quantity documentation to the Project Engineer at the completion of shipments to a project. A designated representative shall sign the certification statement on summary documentation. It shall include type and size, the total quantity of each and the project number.



Acceptance shall be based on the following requirements:


A.  Approved source of metal listed in Appendix A.

B.   Approved source of corrugated metal pipe listed in Appendix B.

C.  Approved coupling devices listed in IM 441.01.

D.  Approved source for coated corrugated metal pipe listed in Appendix D.

E.   Approved source of aprons and end sections listed in Appendix E.

F.   Fabricator certification statement

G.  Proper and complete pipe identification (each pipe, end section, apron, and coupling device shall have the fabricating plant name printed with permanent ink and/or a permanent ‘weather label’ tag attached)



Continued acceptance of brands of metal on the basis of the sheet manufacturer certified analysis and guarantee will be based on satisfactory test results obtained on monitor samples.


Monitor samples of metal may be secured from cut sheets or coils at the fabricator plant or from fabricated pipe at a distributor yard or project site. Monitor samples may be taken at a minimum frequency of one sample annually from the approved fabricator site or supplier site.  Additional monitoring inspection may be required for deficient test results on verification samples, inadequate documentation, or identification of materials.


Monitor samples of metal taken from cut sheets or coils may be at least 4 inches in length by the "as coated" width. Samples taken from fabricated pipe may consist of about 6 inches cut from the end of the pipe. The fabricator or distributor shall provide certified mill test reports and coating weights when monitor samples are secured.


Monitor samples shall include the following:  rivets.


Coupling bands may be checked to verify that they are from an approved source. The manufacturers supplier’s certifications may be reviewed for bolts, nuts, washers, and gaskets used for production.