science

Low-frequency electric resistance weld

Low-frequency electric resistance weld is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Low-frequency electric resistance weld rather than just read about it. In short: Low-frequency electric resistance weld, LF-ERW is Electric resistance welded (ERW) pipe manufactured by cold-forming a sheet of steel into a cylindrical shape. Current is then passed between the two edges of the steel to heat the steel to a point at which the edges are forced together to form a bond without the use of welding filler material.

Key takeaways

Low-frequency electric resistance weld belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Low-frequency electric resistance weld to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Low-frequency electric resistance weld from memory before moving on to harder problems.

Reference excerpt

Low-frequency electric resistance weld, LF-ERW is Electric resistance welded (ERW) pipe manufactured by cold-forming a sheet of steel into a cylindrical shape. Current is then passed between the two edges of the steel to heat the steel to a point at which the edges are forced together to form a bond without the use of welding filler material. Initially this manufacturing process used low frequency A.C. current to heat the edges. This low frequency process was used from the 1920s until 1970. In 1970, the low frequency process was superseded by a high frequency ERW process which produced a higher quality weld. Over time, the welds of low frequency ERW pipe was found to be susceptible to selective seam corrosion, hook cracks, and inadequate bonding of the seams, so low frequency ERW is no longer used to manufacture pipe. The high frequency process is still being used to manufacture pipe for use in new pipeline construction. The Poplar Pipeline was built in the 1950s using pipe made with low-frequency electric resistance welds as was the Pegasus Pipeline.

Poplar Pipeline On January 19, 2015 oil from a broken pipeline seeped into the Yellowstone River, and contaminated the water supply 10 miles south of Glendive, Montana. The release was from Bridger Pipeline LLC's 12-inch Poplar line, which can carry 42,000 barrels a day of crude from the Bakken Formation and runs from Canada south to Baker, Montana. Bridger Pipeline is a subsidiary of True Cos., a privately held Wyoming-based company. The company said in a statement that the pipeline was shut down within an hour of the leak.

Pegasus Pipeline The 2013 Mayflower oil spill occurred when ExxonMobil's 20-inch Pegasus crude oil pipeline spilled near Mayflower, Arkansas on March 29, causing crude to flow through yards and gutters, and towards Lake Conway. Wildlife was coated in some places. Twenty-two homes were evacuated, due to the fumes and fire hazard. Some estimates say the total amount spilled could reach upwards of 300,000 gallons diluted bitumen were spilled. Hook cracks and extremely low impact toughness in the LF-ERW seam were identified as causes of the failure.

Notes and references

Worked examples

Example 1 — a first encounter with Low-frequency electric resistance weld

Start with the simplest possible case. Write down what Low-frequency electric resistance weld claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Low-frequency electric resistance weld before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Low-frequency electric resistance weld ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Low-frequency electric resistance weld

In research: Low-frequency electric resistance weld appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Low-frequency electric resistance weld in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Low-frequency electric resistance weld is common in secondary-school and first-year university syllabi. It links to neighbouring topics Pipe manufacture, so understanding it makes those chapters shorter.
In everyday life: Look for Low-frequency electric resistance weld outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Low-frequency electric resistance weld in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Low-frequency electric resistance weld means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Low-frequency electric resistance weld out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Low-frequency electric resistance weld in simple terms?

Why does Low-frequency electric resistance weld matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Low-frequency electric resistance weld?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Low-frequency electric resistance weld.