Oil lubricated shaft seals and environmental regulations

媒体报道表明，由于轴密封损坏或失败导致世界海洋和海洋污染的润滑油潜在量应该向主管部门发送明确的信息，即这种经常被忽视的污染源需要快速解决。

In its evaluation of news clippings over the course of the past few years, Thordon Bearings found more than 100 references to “propeller shaft seal failure and oil leakage into the sea”, the most recent of which was published in the June 2019 edition of Tanker Operator magazine.

这篇最新文章报告，轴密封件绕螺旋桨轴缠绕后，轴封损坏后的油轮泄漏油。在潜水员在特内里费岛，西班牙的潜水员进行了紧急维修之前，三唇密封泄漏到大海中。

“Regular reports in the maritime technical press and indeed from hull repair specialists themselves show with alarming frequency that the aft seals of oil-lubricated shaft lines are damaged by either ropes or fishing nets and wholly responsible for this source of pollution,” said Craig Carter, Thordon Bearing’s Director of Marketing and Customer Service.

Press releases issued by a well-known underwater ship repair company reference the regularity in which it carries out repairs to damaged seals. One recent report highlighted work to a general cargo ship with a “leaking stern tube assembly”, while another reported repairs to the damaged seals of a semi-submersible offshore platform in Mexico. Yet another reported repairs to a ship leaking oil in Antwerp, after fishing nets had become entwined around the seal assembly.

“这是水下船舶维修公司的良好业务，但这些问题轴密封件，占所有方向线失败的43％，不仅影响海洋环境，而且占船东的底线，”卡特说。

Based on its calculations, Thordon Bearings says that every vessel that operates an oil-lubricated propeller shaft system configured with an aft seal, could be leaking on average 6 litres (1.6 U.S gallons) per day – a statistic backed up by research carried out by New York-based Environmental Research Consulting, which found 240 million litres of operational oil is leaked annually from ships.

Terry McGowan, President and CEO, Thordon Bearings, said: “While the list of vessels that have polluted the oceans following damage to sterntube seals is extensive, it is only a fraction of the number of incidents taking place. The only certainty we have is that the amount of oil discharged into the marine environment from faulty or damaged seals is of significant environmental concern and should be addressed immediately by Administrations and regulators. And this doesn’t even include normal leakage from worn seals.”

When there are cost-effective, environmentally-safe alternatives available, it is understandable why environmental concern abounds, especially given the drive to reduce other forms of shipborne pollution.
Indeed, based on the potential impact of this level of oil pollution in its marine environment, the US EPA recommended that “all newbuild vessel operators endeavor to use seawater-based systems for their sterntube lubrication in order to eliminate the discharge of oil from these interfaces to the aquatic environment”. The EPA has included this clause in its Vessel General Permit rules (sect. 2.2.9) since 2013.

“海事行业继续使用这些系统对清理海洋的优秀工作进行了适得其反的工作，例如，强制性立法减少排放，禁止油性排放或防止外星水生物种的传播。我们现在需要法规来遏制从船的螺旋桨轴泄漏的油流动，“卡特说。

参考去年7月份发布的文章，Carter添加：“船舶洞察杂志质疑我们现在发现自己的环保时间中的油润滑螺旋桨轴继续使用。编辑写道：'用油润滑系统，舷外螺旋桨轴密封件呈现出一定的风险，因为它们预计将实现两种功能，即防止油进入大海，并防止海水进入并污染油。如果密封失败，可能会有操作或环境问题......水润滑的Sterntube解决方案是作为易于的理智方式。我们不能同意更多。“

Thordon Bearings
thordonbearings.com.