API 510 Pressure Testing and Impact Testing: What to Know

All of it comes from the API 510 Body of Knowledge for September 2026, January 2027 and May 2027 (Section I.A, items 6 and 7), read on 26 October 2026. If you test in another window, open that window's edition first.

What the Body of Knowledge lists for pressure testing

Item 6 says the inspector should be able to do four things:

1. Calculate a test pressure that compensates for temperature. The paragraphs named are UG-99 and UG-100.
2. Know the precautions for hydrostatic and pneumatic testing. The BOK gives minimum test temperatures and protection against overpressure as examples.
3. Know all the steps in a hydrotest procedure (UG-99 and UG-100).
4. Know all the steps in a pneumatic test procedure (UG-100 and UG-102).

Only the first is a calculation. The other three are procedure knowledge, and they are the kind of fact that shows up in the closed-book part, where you get 1.5 minutes per question on average. Read the steps in your copy until you can say the order out loud, then check yourself against the paragraph.

What the Body of Knowledge lists for impact testing

Item 7 has two parts:

• Understand the requirements and the procedure for impact testing. The paragraph named is UG-84.
• Determine the minimum metal temperature for a material that is exempt from impact testing. The paragraphs named are UG-20(f), UCS-66 and UCS-68(c).

The second one is a lookup with a short calculation attached. You find the material, find the governing thickness, read the exemption temperature, and sometimes adjust it. The skill is knowing which of those steps your question is asking for, and not reading a number from the wrong column.

Know cold versus look up

The BOK says the closed-book part covers "everyday working familiarity" and the open-book part covers detail you would find in the documents. A sensible split for this topic:

This is our reading of the BOK's closed-book and open-book language, not an API statement of which questions land where. API says the formulas for corrosion rates, remaining life and intervals may be closed-book. It makes no such statement for test pressure, so prepare for both.

A test pressure calculation, step by step

The multiplier and the temperature adjustment are in UG-99 and UG-100, so we do not restate them. What we can do is show the order of work, with invented numbers for the inputs.

1. Find the design pressure and the stress values. On a vessel in service, read them from the nameplate and the material data.
2. Open UG-99 or UG-100 for the test you are asked about. Hydrostatic and pneumatic tests use different paragraphs, and a question will tell you which.
3. Apply the factor and the temperature compensation from the paragraph. Keep a line for each so you can check them if the answer looks odd.
4. Check the units. The BOK says candidates are expected to use both US customary and SI formulas, so a question can arrive in either.
5. Sanity-check the result. A test pressure that is lower than the design pressure is wrong.

Run it five times with different invented values until the paragraph lookup takes under two minutes. The hydrotest pressure calculator lets you check your working once you have the paragraph's inputs. It does not replace opening the code, and it does not tell you which paragraph applies.

An exemption temperature drill

Invent a vessel on paper. Pick a plate material from your own copy of UCS-66, choose a governing thickness, and walk the path:

• Find the material's place in the code's grouping for impact exemption.
• Read the exemption temperature for your thickness.
• Check whether UCS-68(c) offers an adjustment for your case, and what it depends on.
• Write the final minimum metal temperature with its units.

Do it for a thin plate and a thick plate of the same material. The point is to see how the answer moves. A candidate who has done it six times will not hunt for the table during the exam.

Common mix-ups

• Pressure test versus leak test. The BOK items are about UG-99, UG-100 and UG-102. If a question describes a different kind of check, read it twice before you reach for those paragraphs.
• Test pressure versus MAWP. Test pressure is calculated for a test. MAWP is a rating. Our pressure terms article separates the terms.
• Exempt from impact testing versus passed an impact test. An exemption means the code does not require the test at that temperature for that material. It does not mean the material has been tested.
• Hydro precautions versus pneumatic precautions. Learn them as two lists, and learn why the second one is longer.

Where this fits in your plan

If your calculation practice is thin, start with the calculations guide, which maps every BOK calculation to its paragraph. Put test pressure and exemption temperature in the second half of your calculation weeks, after corrosion rate and internal pressure feel automatic. Both depend on looking things up quickly on screen, so add them to your lookup drills as well. For where this sits among the rest of the exam content, see what is not on the API 510 exam.

Check where you stand

The free 10-question API 510 check takes a few minutes and shows which Body of Knowledge areas need work, so you can decide whether testing topics belong in week two or week six. The questions are original and written to API's published content outline. If you want a plan built around your exam date, see the plans. When you are stuck on a paragraph, the study buddy at /study-assistant can walk you through where to look, using your own copy for the numbers.

FAQ

Is the hydrotest calculation on the API 510 exam?

The Body of Knowledge lists calculating a test pressure that compensates for temperature, citing UG-99 and UG-100. Expect it to be possible, and confirm the current list in the Body of Knowledge for your window.

Do I need to memorize test pressure factors?

The BOK does not say the factor will be closed-book. Prepare to find it in UG-99 or UG-100 on screen, and know the logic well enough to spot an answer that is clearly wrong.

What is the difference between an exemption from impact testing and an impact test?

An exemption is a finding that the code does not require impact testing for a given material, thickness and minimum metal temperature. An impact test is the procedure itself, described under UG-84.

Which paragraphs cover a pneumatic test?

The Body of Knowledge cites UG-100 and UG-102 for the steps in a pneumatic test procedure. Read both in your own copy of the Code.

Sources

• API 510 Body of Knowledge, September 2026, January 2027 and May 2027, American Petroleum Institute, Section I.A items 6 and 7 and the note on units, read 26 October 2026
• API 510 exam publications effectivity sheet, September 2026, January 2027 and May 2027, American Petroleum Institute, read 26 October 2026