2016.12.16，美国海岸警备队播发一起还是安全警告，内容涉及MAN B&W系列柴油机缸套冷却水故障，内容大致如下（请以英文原文内容为准）：
近日，一艘700 foot的散货船在驶离columbia 河的过程中发生搁浅（损失和污染可控）。这起事故是由于该轮Mitsui MAN B&W MC-C型两冲程主机缸套冷却水缸套出现裂纹，该裂纹导致柴油机冷却水丧失，最终导致缸盖过热，进而触发主机功能丧失，导致事故的发生。随着对事故调查的深入发现类似的事故多次发生，两年前有一起相似的事故发生在columbia 河，2012年一艘船舶在前往Corpus Christi的过程中，因为同样的原因，失去动力。
（一下部分是事故原理性分析，MAN B&W MC-C型柴油机导致这种事故发生的原因，涉及专业知识，中文翻译很难以保留愿意，此处不做翻译）
On these engines, the outer surface of the lower areas of the engine’s cylinder covers, a.k.a. heads, forms the internal area of the cooling water circuit when the cooling jacket is installed. Water flow from the cylinder liner is directed through four connections into the cooling jacket and then flows upward into other areas of the cylinder cover before exiting. The cooling jacket slips over the bottom of the cylinder cover’s outer surface which has several o-rings that seal the coolant passages. The cooling jacket is held in place by the use of four shoulder type bolts that go through the cooling jacket and into the sides of the cylinder cover. Please watch the following YouTube videos for more information: Video A and Video B.
By design, the shoulders of these bolts are longer than the cooling jacket wall thickness. New replacement bolts will often have even longer shoulders. When the bolts are properly tightened there will likely be a gap between the bottom of the bolt head and the outside of the jacket cover. (Image A) The extra shoulder length allows the cooling jacket to position itself concentrically on the bottom of the cylinder cover and facilitate any movement or slight expansion of the o-rings. It also allows for some expansion of the cast iron cooling jacket. If the cooling jacket is slightly positioned non-concentrically on the cylinder cover, some of the bolt head’s bottom surface areas may appear as if the bolt is fully tightened against the outside of the jacket cover.
断裂照片
正确紧固螺栓
USCG建议：
1、相关各方应确保船方获得设备服务商提供的服务信息渠道畅通。
2、船舶轮机员（工作于安装MAN B&W MC-C系列柴油机船舶）应意识到装配过程中使用shoulder bolts的潜在风险。不应使用regular bolts with no shoulders螺栓。
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