机电采购里非常典型的翻车，不是买贵了，而是“参数全对、实物全错”。桥架这东西藏在吊顶和管廊里，不扒开看根本发现不了猫腻。

The most typical failure in mechanical and electrical procurement is not buying too expensive, but rather "all parameters are correct, but all physical items are wrong". The bridge in eastern Xizang is in the ceiling and pipe gallery. If you don't open it up, you can't find anything fishy.

先盯三张“身份证”，比听销售讲故事管用：

Focus on three "ID cards" first, which is more effective than listening to salespeople tell stories:

板厚拿卡尺说话。标1.5mm的钢制桥架，到货实测只有1.2mm，大跨距中段必下挠。宽度≤150mm至少1.0mm，150~300mm至少1.2mm，300~600mm至少1.5mm，别信样品、只信大货抽检。

Plate thickness speaks with a caliper. The steel bridge frame with a standard of 1.5mm was only measured to be 1.2mm upon arrival, and the middle section of the large-span must be bent downwards. Width ≤ 150mm, at least 1.0mm; 150-300mm, at least 1.2mm; 300-600mm, at least 1.5mm. Do not trust samples, only bulk sampling.

锌层看工艺不看名字。室内干燥用电镀锌（≥12μm）就行；地下室、户外、管廊直接热浸锌，平均锌层≥65μm，局部不低于52μm。很多低价单把“冷镀”当“热镀”报，半年就起红锈。

The zinc layer depends on the process, not the name. Indoor drying requires electroplating with zinc (≥ 12 μ m); The basement, outdoor, and pipe gallery are directly hot-dip galvanized, with an average zinc layer of ≥ 65 μ m and locally not less than 52 μ m. Many low-priced orders mistake "cold plating" for "hot plating" and start to rust after six months.

载荷要等级不要形容词。让厂家写明SWL等级（A~D）和对应挠度——钢制满载挠度≤跨距/200。只写“承重力强”的，验收时一踩一个坑。

The load should be graded without adjectives. Ask the manufacturer to specify the SWL grade (A~D) and corresponding deflection - steel full load deflection ≤ span/200. Only write 'strong load-bearing capacity', step on one pit during acceptance.

再查三处容易漏的辅料：

Check three more easily leaked auxiliary materials:

连接片、托臂、螺栓建议和主桥架同工艺防腐，黑件螺丝配热镀桥架，整套系统先从配件烂起。

The connecting pieces, support arms, and bolts must be anti-corrosion treated in the same process as the main bridge frame. The black screws should be matched with hot-dip plated bridge frames, and the entire system should start from the failure of the accessories.

弯通、三通别现场锯角铁拼，原厂弯通内侧半径≥电缆非常小弯曲半径（通常≥10D），硬折会把电缆绝缘挤破。

Bent and tee joints should be spliced with angle iron on site. The inner radius of the original bent joint should be greater than or equal to the minimum bending radius of the cable (usually greater than or equal to 10D). Hard bending may cause insulation damage to the cable.

伸缩节和接地。钢制直线段超30m、铝合金超15m建议加伸缩节；镀锌桥架连接板两端至少2颗防松螺栓，非镀锌的用≥4mm²铜绞线跨接，全长两头加中间每20~30m一点接地。

Expansion joints and grounding. Expansion joints must be added for steel straight sections exceeding 30m and aluminum alloy sections exceeding 15m; At least 2 anti loosening bolts should be installed at both ends of the galvanized bridge connecting plate, and non galvanized ones should be bridged with ≥ 4mm ² copper stranded wire. The entire length should be grounded at both ends with a point every 20-30 meters in the middle.

非常后一条合同红线：把“执行JB/T 10216、锌层厚度、板厚公差、随货第三方检测报告”写进附件，拒收条款写清楚。不然退货时对方掏出聊天记录说“当初没约定”，你连扯皮的凭据都没有。

The last red line of the contract: include "execution of JB/T 10216, zinc layer thickness, plate thickness tolerance, and third-party inspection report accompanying the goods" in the attachment, and clearly state the rejection clause. Otherwise, when you return the item, the other party will take out their chat records and say 'there was no agreement at the beginning', and you won't even have any evidence to argue.

把“板厚实测、锌层工艺、辅料同标”这三件事钉在验货单上，隐蔽工程一次过审的概率会高很多。

Pin the three items of "actual measurement of plate thickness, zinc layer process, and same standard of auxiliary materials" on the inspection sheet, and the probability of concealed works passing the first review will be much higher.