· Difference of the thread structure (datum mark-All products);

· Difference ofhardness test position (NS-1 increase full cross section hardness test-all products);

·Cold rolling requirements (the clear requirements of the thread and stress-reducing groove for cold rolling treatment, and drill collar hanging cards, slips root fillet of the rolling requirementsinNS-1-all products);

· The difference of impact work (part of the product requirements under low temperature -20℃ conditions test of NS-1 );

· The difference of wall thickness difference (The requirement of full length wall thickness difference and both ends wall thickness difference in NS-1 );

· Product marking groove type and position requirements;

· Requirements for specific dimensions of wear-resistant belt welding type;

· Other recommended requirements.