An explosion occurred during hot work activities, killing three contract workers and injuring seven others.

在高溫作業活動中發生爆炸，造成三名合同工死亡，七人受傷。

The DeRidder mill produces container board that is used in products such as boxes and cardboard displays.

DeRidder 工廠生產用於包裝箱和紙板展示架等產品的箱板紙。

The container board is made from pulp produced at the facility.

貨櫃板是用該設施生產的紙漿製成的。

During the process of creating pulp, vapors are generated.

在製造紙漿的過程中會產生蒸汽。

These vapors, which contain water, turpentine and various sulfur compounds, are collected and separated.

這些含有水、松節油和各種硫化合物的蒸汽被收集並分離出來。

To separate the vapors, they first enter a turpentine stripping column.

為了分離蒸氣，蒸氣首先進入松節油汽提塔。

There, most of the turpentine is removed and sent to a condenser.

在這裡，大部分松節油被去除，然後送入冷凝器。

The remaining vapors in the stripper condense to a liquid, containing mostly water, but also residual amounts of sulfur compounds and turpentine.

汽提塔中剩餘的蒸汽會凝結成液體，其中大部分是水，但也有殘留的硫化合物和松節油。

This liquid is known as foul condensate.

這種液體被稱為汙濁冷凝液。

The foul condensate is sent from the stripping column to an approximately 100,000-gallon capacity atmospheric storage tank, used to store the liquid at or close to ambient pressure.

汙濁的冷凝水從汽提塔被送入一個容量約為 100,000 加侖的常壓儲罐，用於在環境壓力或接近環境壓力的條件下儲存液體。

The foul condensate tank is primarily used to regulate the flow of liquid between the turpentine stripping column upstream and a downstream unit that removes the remaining sulfur components from the water.

汙物冷凝液罐主要用於調節上游松節油汽提塔與下游裝置之間的液流，下游裝置用於去除水中剩餘的硫成分。

During the February 8th incident, the mill was undergoing its annual shutdown.

2 月 8 日事件發生時，工廠正在進行年度停工。

The shutdown required mill employees and contract workers to perform maintenance, inspection and upgrade tasks throughout the facility.

停產要求工廠員工和合同工對整個設施進行維護、檢查和升級。

One of these tasks was the repair of water piping, located above and connected to the foul condensate tank that had shifted and cracked months earlier.

其中一項任務是修復位於汙物冷凝槽上方並與之相連的水管，該管道在幾個月前發生了移位和裂縫。

The repair required welding on the piping, commonly referred to as hot work.

維修需要在管道上進行焊接，通常稱為熱作業。

In preparation for the hot work, valves were closed leading into and out of the foul condensate tank, while ten feet of liquid remained inside.

為準備高溫作業，進出汙濁冷凝液罐的閥門被關閉，而罐內仍有 10 英尺深的液體。

The liquid was left within the tank, partially because there were no plans to work directly on the tank during the outage.

這些液體被留在油箱內，部分原因是在停運期間沒有計劃直接在油箱上施工。

The company also assumed that the tank contained mostly water, was sealed off from the atmosphere and did not pose a safety risk.

該公司還假定，罐內大部分是水，與大氣隔絕，不構成安全風險。

These assumptions were, however, incorrect.

然而，這些假設並不正確。

Residual turpentine, normally present in foul condensate, collected on the top of the liquid in the tank due to its density.

殘留松節油通常存在於汙濁的冷凝水中，由於其密度較大，會聚集在罐中液體的頂部。

The foul condensate tank was designed so that by changing the height of the liquid level inside the tank, the residual turpentine would be skimmed off and sent to a turpentine recovery system.

汙濁冷凝液罐的設計目的是，通過改變罐內液麵高度，撇去殘留松節油，並將其送入松節油回收系統。

But in the months leading up to the incident, the turpentine was not removed, because there was confusion as to who at the mill was responsible for operation of the foul condensate tank.

但在事件發生前的幾個月裡，松節油並沒有被清除，因為工廠裡誰負責汙濁冷凝液罐的操作出現了混亂。

Due to this confusion, a valve designed to direct skimmed turpentine to the mill's turpentine recovery system remained closed for months.

由於這種混亂，一個用於將脫脂松節油導入工廠松節油回收系統的閥門數月來一直處於關閉狀態。

As a result, leading up to the incident, more flammable turpentine was present in the foul condensate tank than anyone expected.

是以，在事故發生之前，汙物冷凝罐中的易燃松節油比任何人預想的都要多。

In addition, there are normally vapors inside the foul condensate tank in the space above the liquid.

此外，汙物冷凝槽內的液體上方空間通常會有蒸汽。

Although those vapors can become flammable, they are supposed to be kept at a concentration that is too rich to burn.

雖然這些蒸氣可能會變成易燃物，但其濃度應該保持在無法燃燒的範圍內。

But due to the non-routine conditions experienced during the annual shutdown, the contents of the tank likely cooled, creating low pressure within the tank.

但由於在年度停機期間經歷了非例行條件，油箱內的物質可能冷卻，造成油箱內壓力過低。

This most likely triggered a relief valve on the tank's roof to add more air, to avoid damaging the tank from the vacuum created by low pressure.

這很可能觸發了油箱頂部的洩壓閥，以增加空氣，避免因壓力過低產生真空而損壞油箱。

The vacuum relief valve was likely one of the few potential sources that allowed enough air into the tank to create an explosive atmosphere.

真空洩壓閥很可能是允許足夠的空氣進入油箱以產生爆炸氣氛的少數潛在來源之一。

In preparation for the hot work, the water piping was isolated from the foul condensate tank and the rest of the process by closed valves and the piping was separated physically from the tank.

在準備熱工作業時，水管與汙物冷凝液罐和其他工藝通過封閉閥門進行了隔離，管道與罐體也進行了物理隔離。

Around 8 a.m. on February 8th, a mill employee used a gas detector to check for a flammable atmosphere in and around the water piping and found none.

2 月 8 日上午 8 點左右，一名工廠員工使用氣體檢測儀檢查水管內部和周圍是否存在可燃氣體，結果沒有發現可燃氣體。

As a result, the company issued a hot work permit for the welding work.

是以，公司為焊接工作頒發了高溫作業許可證。

But even though a flammable atmosphere was not present outside the tank, there was a flammable atmosphere inside the tank.

但是，儘管罐外沒有易燃氣氛，罐內卻存在易燃氣氛。

Without knowing that the tank posed a serious hazard, three contract workers began welding on the water piping located above it.

三名合同工在不知道水箱存在嚴重危險的情況下，開始焊接水箱上方的供水管道。

The CSB was unable to determine an exact ignition source, but it is likely that sparks or molten slag produced from the hot work landed on or near the foul condensate tank, heating up the tank wall or otherwise igniting the contents inside.

CSB 無法確定確切的點火源，但很可能是高溫作業產生的火花或熔渣落在了汙濁的冷凝液罐上或附近，加熱了罐壁或點燃了罐內的物品。

Or it is possible that the hot work was complete, but as the tools were lowered, a welding torch fell and created an electric arc on the tank or its vent piping.

也有可能是熱作業已經完成，但在放下工具時，焊槍掉落，在罐體或其通風管道上產生了電弧。

Regardless, the CSB determined that hot work activities likely ignited the flammable vapors and liquid turpentine inside the foul condensate tank.

無論如何，CSB 認定熱作業活動很可能點燃了汙垢冷凝液罐內的易燃蒸汽和液態松節油。

At 11.05 a.m., there was a large explosion.

上午 11 時 05 分，發生了大爆炸。

The tank separated from its base and launched up and over a six-story structure, landing approximately 375 feet away.

坦克從底座分離，發射升空，越過一座六層高的建築，落在大約 375 英尺外的地方。

Three people were killed and seven were injured.

3 人死亡，7 人受傷。

All were contract employees working near the foul condensate tank.

他們都是在汙物冷凝槽附近工作的合同工。