Based on the principles used in ASME VIII-1 and other codes, the comparison of design methods for the cylinder subjected to external pressure in AD code and ASME VIII-1 was carried out.

On the basis of the calculation method for the cylinder subjected to external pressure and the relevant content in ASME VIII-1, the revision of the calculation for the cylinder subjected to external pressure was discussed in this paper.

According to stability theory and design method of external pressure cylinder,the experience which can improve technology parameter by the way cutting open clamp ferrule to change effective length of external pressure cylinder is introduced.

Thevariation laws of the thickness irregularity andout-of-roundness of the tube while expanding are investigated.

This paper specifically analyzes the philosophy of requirements of permissible out-of-roundness for shells, of shape tolerance for heads, and of alignment tolerance for sections at edges to be welded which are specified by ASME Boiler and Pressure Vessel Code.

Through designing for finishing pass and ana lysing for rolling shaped of round bar,puts forward reasonable determining metho d for out of roundness of round bar produced by national standard and the devel oping trend of round bar finishing pass design.

It makes an overall analysis of the tread damage(flaking)and the occurrence of the wheel out of roundness in terms of the wheel skidding load and the wheel material,and finally puts forward the measures to be taken to avoid or reduce the wheel damage.