欧美精品国产综合久久_国产免费观看久久黄av片_欧美一级特黄啪啪片免费看_天美影视传媒有限公司官网免费网站大全下载_污污内射久久一区二区欧美日韩_富婆被大肉楱征服小说_国产精欧美一区二区三区_她看向窗外_亚洲成av人片不卡无苍井空

Corrosion prevention is the use of various methods to protect metal objects that are prone to rusting, in order to extend their service life. Generally, physical corrosion prevention, chemical corrosion prevention, electrochemical corrosion prevention, and other methods are used.

The anti-corrosion level is classified into the following five levels according to indoor and outdoor:

It can be seen that WF1 and F1 are respectively of the outdoor moderate corrosion protection type and the indoor moderate corrosion protection type. These two corrosion protection levels are applicable to different environmental conditions and are not comparable.
Service Hotline: 18924609560 (same WeChat account)