The Difference Between Ductile Iron Pipes K7 and K9

Ductile iron pipes designated K7 and K9 are differentiated by their wall thickness grades and are used in different pressure environments. The distinctions between them are as follows:

This non-standard ductile iron pipe features reduced wall thickness and pressure-bearing capacity, suitable only for certain low-pressure applications.

Grade K7

Compliant with national standards for ductile iron pipes, these products adhere to stringent quality specifications regarding wall thickness, performance characteristics, and pressure ratings, making them suitable for high-pressure applications

Grade K9

Grade K7

Thinner wall thickness reduces costs by decreasing molten iron pouring volume, making it suitable for applications with low pressure requirements.

Grade K9

Wall thickness meets standards and complies with national pressure rating specifications. Its wall thickness design enables it to withstand higher internal pressures and external loads, offering enhanced safety. It is widely employed in high-pressure applications or critical engineering projects.

Appendix:K9 Grade Theoretical Weight Table

Grade K7

Capable of withstanding pipeline pressures below 1.0 MPa.

Grade K9

Capable of withstanding pipeline pressures exceeding 1.6 MPa.

Grade K7

Suitable for certain low-voltage applications.

Grade K9

Suitable for high-pressure water supply and industrial water applications where stringent pressure requirements exist, such as long-distance water conveyance, complex geological conditions (high groundwater levels, areas subject to heavy traffic loads), or main pipeline networks requiring long-term stable operation.

Grade K7

Owing to its relatively thin walls, production costs are comparatively low, resulting in a more affordable price.

Grade K9

Due to its higher standards and performance, the price will be higher than that of the K7 class.

K9 pipes clearly display production information such as grade and standards on the pipe body.

K9 pipes have thicker walls (e.g., for DN100 pipes, K9 wall thickness is approximately 6.2mm, while K7 is about 5.0mm).

Review the inspection reports and certification details, including parameters such as pressure rating and spheroidisation rate.

When selecting ductile iron pipes, the appropriate grade should be determined based on specific project requirements, budgetary constraints, and pipeline operating pressures. Concurrently, attention must be paid to factors such as the product's anti-corrosion treatment process, as these also influence the overall performance and service life of the pipeline.

Shanxi Jintaihongye Casting & Forging Machinery Co., Ltdsituated in Shanxi Province, China,is one of the leading manufacturers of ductile iron pipe fittings, pipelines, various valves, and manhole covers, leveraging the region's abundant industrial raw materials.

For more information, please contact us : WhatsApp/WeChat: +86 18334738900

Email address:info@jthypipe.com;jthypipeamy@126.com