The rush of master limited partnerships going public continues unabated through the second quarter of 2013. As the month of June draws to a close, let's look back at all that we have gained this quarter in the wonderful world of MLP IPOs.

April
Kicking off the second quarter right, KNOT Offshore Partners (NYSE:KNOP) debuted on April 10. The partnership owns and operates shuttle tankers under customer contracts that last five years or more. Knutsen NYK Offshore Tankers (KNOT) controls the 2% general partner stake and all the incentive distribution rights. Shuttle tankers move crude oil and condensate from offshore oil rigs to onshore terminals and refineries, so it makes sense that KNOT Offshore's customers include BG Group, Statoil, and Transpetro. 

May 
We had two MLP IPOs in May. First up was Emerge Energy Services (NYSE:EMES), which hit the books on May 9, and is up 16% already. The partnership has a sand segment and a fuel processing and distribution segment, which engages primarily in the separation of transmix.

Tallgrass Energy Partners (NYSE:TEP) followed closely behind, going public on May 14. This midstream company picked up some of Kinder Morgan Energy Partners' western-based natural gas assets when KMP was forced to divest them to receive the Department of Justice's blessing on the El Paso acquisition.

June
June was a little light on MLP IPOs. In fact, there weren't any. Brookfield Renewable Energy Partners priced on June 11, but then postponed its offering on June 20.

What June did bring, however, was a few announcements about IPOs planned for later this year. Devon Energy (NYSE:DVN) announced it would pursue the IPO process for its midstream assets, while Enbridge Energy Partners (NYSE:EEP) announced it would spin off some of its assets to form Midcoast Energy Partners. Midcoast has some intriguing natural gas and natural gas liquids assets in Texas and Oklahoma.

World Point Terminals and OCI Partners also filed initial IPO paperwork. Not surprisingly, World Point Terminals is in the storage business, focused mainly on refined products and crude oil. OCI Partners is in the methanol and ammonia business, and is currently the largest merchant methanol producer in the U.S.

Bottom line
Keeping track of all of these IPOs is the first step, digging in to find the best opportunities for investment is the second. Don't let due diligence be swept away in the rising tide of MLP IPOs, they are not all created equal.

Fool contributor Aimee Duffy has no position in any stocks mentioned. If you have the energy, follow her on Twitter: @TMFDuffy.

The Motley Fool recommends Statoil (ADR). The Motley Fool owns shares of Devon Energy. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.