Yes, when purchasing steel, the supplier should provide a material certificate along with the goods. This is both a regulatory requirement and standard practice in the steel trade. The material certificate serves as the steel's "ID card," recording key information such as the batch number, heat number, chemical composition, and mechanical properties; it is the essential document verifying that the steel meets quality standards, contractual terms, and national specifications.
Procurement contracts should explicitly require the supplier to provide the original manufacturer's material certificate bearing an official company seal. Upon receipt of the goods, it is crucial to verify that the heat and batch numbers on the certificate match those on the physical tags attached to the steel, and to ensure that the seal and data on the certificate are complete and legible. If you have any doubts regarding the authenticity of the material certificate, you may also request third-party testing to verify the goods.

Price discrepancies are common in the procurement of anti-corrosion steel pipes. This is mainly because the final price is affected by multiple factors, including the type of anti-corrosion treatment, the base pipe itself, specifications, procurement volume, and market transportation.
The cost of basic seamless pipe and welded pipe substrates is relatively transparent, with limited price differences. The main fluctuation range comes from the materials used for anti-corrosion coatings and the construction process. Even for the same type of corrosion protection, different grades can have vastly different prices.
For example, the price difference between ordinary and reinforced 3PE anti-corrosion coatings (thicker polyethylene layer, stricter requirements) can be more than double. The cost of anti-corrosion coating processing varies depending on the process and materials. Standard anti-corrosion construction includes multiple processes such as pipe pretreatment, rust removal, primer, and topcoat. Reputable manufacturers strictly follow the standards for rust removal, ensuring that the coating thickness meets the requirements and the anti-corrosion service life meets the design life.
Some factories simplify the rust removal process by directly applying anti-corrosion materials. However, the coating has insufficient adhesion, and after only a few years of underground use, the coating peels off, and the pipes quickly rust and leak. Although the purchase price is lower, the pipes are repaired and replaced in advance, which significantly increases the long-term maintenance cost.
When requesting quotations, specify all parameters, including the base pipe material, pipe diameter and wall thickness, type and thickness of the anti-corrosion coating, and applicable standards, to ensure that quotations from different suppliers are based on the same standard.

The primary differences between NM400, NM450, and NM500 wear-resistant plates lie in their hardness, processing techniques, welding performance, costs, and market prices.
NM400 has a hardness range of 350–450 HB, whereas NM500 is harder, with a range of 480–560 HB. This means NM500 offers superior wear resistance, making it suitable for more demanding operating environments.
The two types of plates involve different processing techniques, which affect their costs and market prices. Due to the greater difficulty involved in processing NM500, production costs are relatively higher; consequently, its market price is generally higher than that of NM400.

NM400 (360–440 HBW), offers the best toughness and workability; suitable for operating conditions involving moderate wear and some impact; a cost-effective choice for routine wear applications.
NM450 (420–480 HBW), features 15%–30% higher wear resistance than NM400 and strikes a superior balance between hardness and toughness; the best value-for-money choice for most applications.
NM500 (470–530 HBW), boasts the highest hardness and superior wear resistance, with a service life 1.8–2.5 times that of NM400 under extreme wear conditions. However, it has the lowest toughness and presents challenges—as well as higher costs—regarding processing and welding; it is suitable only for extreme wear environments with low or no impact.
The choice of wear-resistant plate should be based on a comprehensive assessment of wear intensity, impact loads, processing requirements, and budget.